Method for welding at least two components, and laser welding device

Abstract

The invention relates to a method for welding at least two components (12) along a welding path (16) running on a component surface (10) of at least one of the components (12), in which at least three laser beams (14), in particular 5 to 30 laser beams (14), are simultaneously directed onto the welding path (16) one behind the other, and are moved over the component surface (10) at the same feed speed in a welding direction (20) running along the welding path (16), wherein laser power is introduced into at least one of the components (12) by means of each of the laser beams (14) during the movement of the laser beams (14) in the welding direction (20). (Fig. 1)

Description

[0001] TRUMPF Laser and System Technology SE DS16766P4241 WOO

[0002] March 31, 2025

[0003] 1

[0004] METHOD FOR WELDING AT LEAST TWO COMPONENTS AND LASER WELDING DEVICE

[0005] The invention relates to a method for welding at least two components along a welding path running on a component surface of at least one of the components and to a laser welding device for welding two components.

[0006] When welding components using a laser beam, especially at high speeds, welding defects such as humping, spatter, and ejections, as well as pores, cracks, and edge notches, can occur. Humping is the formation of molten masses during solidification. These molten masses occur particularly at high welding speeds and result from cyclical pinching and accumulation of the melt during the after-run. The greater the dynamics of a melt pool generated during melting, the greater the risk of humping. The risk of humping is particularly high in continuous welding processes with high welding speeds.

[0007] The object of the present invention is to enable welding of at least two components at high welding speed with a particularly low risk of welding defects.

[0008] The object is achieved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are specified in the subclaims, the description, and the drawings. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0009] The invention relates to a method for welding at least two components along a weld path running on a component surface of at least one of the components. Welding is a group of joining methods for permanently joining two or more components. Laser welding is primarily used for welding components that are to be joined at high welding speeds, with a narrow and slender weld seam shape, and with low thermal distortion. Laser welding is generally carried out without the addition of a filler material. In laser welding, laser radiation is focused using at least one optical system. The method provides for at least three laser beams, in particular five to 30 laser beams, to be aligned simultaneously one after the other onto the weld path.This means that the at least three laser beams impinge simultaneously on the weld path and thus on the at least one component surface of the at least one component. The laser beams impinge on different points along the weld path. The method further provides for the laser beams to be moved across the component surface at the same feed rate in a welding direction running along the weld path. In particular, it can be provided that the weld path is traversed successively, at least in a length range, by all laser beams arranged one behind the other in the feed direction.

[0010] It can be provided that, while the laser beams are moved in the welding direction, laser power is continuously introduced into at least one of the components by means of each of the laser beams. This allows a continuous introduction of laser power into at least one component by means of all of the laser beams while the laser beams are moved in the welding direction. In this case, it is provided in particular that the laser beams are moved at the same feed speed, in particular in the same welding direction, thereby ensuring that the relative position of the respective points of impact of the laser beams on the welding path remains constant during the welding of the components. A laser welding device providing the laser beams can be operated in continuous operation. This means that the laser beams are generated without interruption, i.e. continuously, and are aligned with the welding path.This continuous operation can also be described as continuous wave (CW) operation. Because at least three laser beams are aligned one after the other in the welding direction onto the weld path, the melt generated by welding solidifies particularly slowly in the wake of a process zone—due to the elongation of the molten pool—which makes it particularly effective in preventing the aforementioned welding defects, even at high welding speeds.

[0011] Alternatively, at least one of the laser beams can be provided with pulsating intensity. Providing the laser beams with pulsating intensity enables the weld seam to be created from a plurality of welding spots arranged one behind the other along the welding path. To achieve the pulsating intensity of the laser beams, the power of the laser beams is changed at regular intervals, in particular increased and decreased. In particular, the provision of the respective laser beams can be reduced to zero at regular intervals for a predetermined time interval, thereby separating two processing pulses of the respective laser beams from one another. In this pause between two processing pulses of a respective laser beam, the melt generated during the respective previous processing pulse of the laser beam can cool and thereby solidify.The humps mentioned above occur particularly during continuous wave welding at very high welding speeds. The cause of these humps, also known as humping, is cyclical pinching and backing up of the melt during the downstream process. Pulsed processing with laser beams delivered at pulsating intensity allows for particularly low melt pool dynamics. As a result, pinching of the melt is avoided, meaning no humping occurs. In particular, the intensity of the laser beams is varied from 0 to 100% during a processing pulse.

[0012] It can be provided that the plurality of laser beams are arranged on the component surface in the longitudinal direction of the welding path at a distance from one another which is greater than a diameter of an image of the respective laser beam on the component surface. In other words, a period length of a processing pulse of the laser beam is shorter than a period length with which the laser beam is offset by the amount of a first spatial direction. It is thus possible for the components to be welded together at several points along the welding path during a first processing pulse of the laser beam. Subsequently, after a pause, a second processing pulse of the laser beams can be emitted, during which the components are welded together at respective points on the welding path which, in the longitudinal direction of the welding path, lie between the welding points created during the previous processing pulse.Since no continuous line is drawn along the longitudinal direction of the welding path by means of the respective laser beams and the respective melt pools generated per processing pulse of the laser beam only have a particularly small extent in the longitudinal direction of the welding path, welding defects such as so-called humping can be particularly well avoided.

[0013] It is possible for at least one of the laser beams, in particular all of the laser beams, to be moved over the component surface at a speed of at least 2 m / s. The components can therefore be welded together particularly quickly within the scope of the process. At the same time, the pulsed provision of the laser beams described above means that, despite the particularly high welding speed, the risk of humps and thus hills in the weld seam can be kept particularly low. Within the scope of the process, it is particularly provided that the laser beams are moved at a feed speed of 50 mm / s to 10,000 mm / s, in particular of 200 mm / s to 5,000 mm / s.

[0014] It can further be provided that at least one of the following properties is set for respective processing pulses of the at least one pulsed laser beam. If a plurality of laser beams are to be pulsed, the same properties can be selected for all of these laser beams for respective processing pulses. As a property, a processing pulse frequency of 1 kHz to 50 kHz, in particular of 5 kHz to 10 kHz, can be set. Alternatively or additionally, a peak power of the processing pulse of 1 kW to 20 kW, in particular of 2 kW to 8 kW, can be set as a property. Alternatively or additionally, a processing pulse duration of 10 microseconds to 100 milliseconds, in particular of 50 microseconds to 50 milliseconds, can be set as a property of the respective processing pulse. Alternatively or additionally, a feed rate of 50 mm / s to 10,000 mm / s, in particular of 2,000 mm / s to 5,000 mm / s, can be set as a property.000 mm / s can be set.

[0015] It can be provided that the at least one laser beam is provided with pulsating intensity in linear sections of the welding path and is thus pulsed, and the curved sections of the welding path are welded by means of at least one unpulsed laser beam. This means that the laser beam is provided with constant intensity in the curved sections of the welding path, so that the components in the region of these curved sections of the welding path can be welded, for example by means of continuous wave welding. This can result in a particularly precise course of a weld seam created on the welding path. This can ensure that the linear sections of the welding path can be welded particularly quickly, whereas the curved sections of the welding path can be welded particularly precisely.

[0016] In a possible further development of the invention, the laser beams are arranged one behind the other in a (straight) line. This makes it possible to weld a straight and thus linear section of the weld path particularly quickly. The linear arrangement of the laser beams allows the molten pool to be extended particularly reliably, in particular from the first of the laser beams arranged in a line to the last laser beam arranged in the line along the welding direction. As a result, the melt solidifies particularly slowly in the follow-up, which makes it particularly easy to avoid welding defects such as humping, especially at high welding speeds.

[0017] In a further possible embodiment of the invention, respective parameters are set for at least one of the laser beams in such a way that a vapor capillary is created. This vapor capillary can also be referred to as a so-called keyhole. It is possible for the parameters for the respective laser beams to be set in such a way that one of the laser beams leading along the welding path with respect to the welding direction does not create a vapor capillary, for example due to thermal conduction welding, and at least one of the laser beams trailing along the welding path in the welding direction creates a vapor capillary, thus resulting in deep welding. This makes it particularly effective to prevent welding defects such as humping.

[0018] In this context, it can be provided, in particular, that the respective parameters for all laser beams are set such that one vapor capillary is generated per laser beam. This means that, for example, based on a selected laser power for each of the laser beams or based on a selected distance between the respective images of the laser beams impinging on the weld path, a vapor capillary is generated by each laser beam in at least one of the components. The more of the laser beams that each generate a vapor capillary, the better humping and, in general, welding defects are prevented.In a further possible embodiment of the invention, it is provided that a distance between the centers of images of two laser beams arranged one behind the other along the welding path is greater than at least 20 percent of a width of a weld seam produced by welding, said width running perpendicular to the welding direction and on the component surface. In particular, it is provided that the distance between the centers of the images of the two laser beams arranged one behind the other along the welding path is greater than at least 25 percent of the width of the weld seam produced by welding. The greater the distance between the respective centers of the images of the laser beams arranged directly behind one another along the welding path, the more reliably a separate vapor capillary can be generated for each of the laser beams.The distance between the laser beams directly adjacent to each other in the welding direction or along the weld path should be kept at a maximum of such a large distance that a continuous melt pool is created by all laser beams simultaneously directed onto the weld path. This allows welding defects such as humping to be reliably avoided, especially at very high welding speeds.

[0019] In a further possible embodiment of the invention, a distance between the centers of images of two laser beams arranged one behind the other along the welding path is greater than a diameter of the respective images. This can stabilize the at least one vapor capillary created, which in turn stabilizes the energy input of the respective laser beams into the at least one component. Furthermore, this can achieve a precise welding depth for the entire weld seam path, whereby a particularly high gas tightness of a weld seam created during welding can be achieved.In addition, if the distance between the centers of the images of the laser beams directly adjacent to each other along the welding path is greater than the diameter of the respective images, it can be achieved that a particularly long molten pool is generated by means of the laser beams, whereby particularly high welding speeds can be implemented when welding the components due to the reduced risk of welding defects.

[0020] In a further possible embodiment of the invention, it is provided that a first distance between the centers of two images of respective laser beams arranged directly one behind the other in the feed direction and a second distance between the centers of two images of respective laser beams arranged directly one behind the other along the welding path differ from one another by at least 5 percent, in particular by at least 10 percent, in particular by a maximum of 500 percent. In this case, the percentage refers in particular to the smaller distance. In other words, it is provided that not all laser beams arranged one behind the other in the feed direction have the same distance from the respective leading or trailing laser beams.By specifically adjusting the distances between the laser beams, the resulting melt pool and vapor capillaries can be adjusted. This stabilizes the individual vapor capillaries and improves weld quality, preventing humping, spatter, pores, and weld collapse. Furthermore, by lengthening the melt pool and stabilizing the individual vapor capillaries, the feed rate can be increased without causing weld defects.

[0021] This is based on the knowledge that in laser welding with a multi-spot line, i.e. with several laser beams arranged one behind the other in the feed direction, particularly high welding speeds are possible by extending the molten pool and the molten pool can be stabilized by creating separate vapor capillaries. If the distance between laser beams arranged directly behind one another in the feed direction is the same, the laser beams can create open or closed vapor capillaries. If a process regime switches back and forth between closed and open vapor capillaries during the welding process, process instabilities and welding defects can occur. If the distance between laser beams arranged directly behind one another in the feed direction is the same, instabilities can arise if trailing vapor capillaries coalesce and cause turbulent melt pool dynamics.This coalescence of the trailing vapor capillaries can be avoided by carefully adjusting the distances between the laser beams.

[0022] In this context, it is particularly intended that the distances between the centers of the images of the laser beams increase against the feed direction. In other words, the distances between respective laser beams arranged one behind the other in the feed direction become greater the further back the respective laser beams are located in the row of laser beams running in the feed direction. The further back a respective laser beam is arranged in the row, the greater the distance this laser beam is from the laser beam immediately ahead in the feed direction. Due to the molten pool heating up against the feed direction, an increasing distance between the laser beams against the feed direction enables particularly high efficiency. This means that very little energy is required to weld the at least two components.

[0023] In this context, it can alternatively be provided that the distances between the centers of the images of the laser beams decrease against the feed direction. In other words, the distances between respective laser beams arranged one behind the other in the feed direction become smaller the further back the respective laser beams are located in the row of laser beams running in the feed direction. The further back a respective laser beam is arranged in the row, the smaller the distance between this laser beam and the laser beam immediately ahead in the feed direction. A greater distance between the laser beams in the lead allows for preheating of at least one of the components or cleaning of at least one of the components. This allows the components to be joined together particularly securely by means of a particularly high-quality weld seam.

[0024] In a further possible embodiment of the invention, at least one of the distances between the centers of two images of laser beams arranged directly one behind the other in the feed direction is greater than the distance immediately preceding the feed direction and the distance immediately following the feed direction. In other words, this greater distance represents at least a local maximum of the distances. This local maximum with respect to the distances allows for temporarily reduced laser power to be introduced into the molten pool due to the increased distance, thereby preventing overheating of the molten pool. By adjusting the length of this distance, the temperature development of the molten pool can be specifically controlled.

[0025] In a further possible embodiment of the invention, at least one of the distances between the centers of two images of laser beams arranged directly one behind the other in the feed direction represents an absolute maximum of the distances, in that, starting from this distance, the further distances between respective centers of images of laser beams arranged directly one behind the other in the feed direction decrease in and / or against the feed direction. The distance in question is thus the longest compared to all other distances of the laser beams arranged one behind the other in the feed direction. The further a respective distance is located from this distance representing the maximum, the smaller the respective distance.This makes it possible to achieve a particularly low temperature gradient, particularly in the wake of the melt pool, which means that humps, pores and collapse of the weld seam can be particularly effectively avoided during the solidification process of the melt.

[0026] In a further possible embodiment of the invention, it is provided that the laser beams arranged in a row in the feed direction form at least two clusters, wherein the distances between the images of laser beams of a common cluster arranged directly one behind the other in the feed direction are less than 1.5 times the diameter of the image of one of the laser beams of the cluster. It is therefore provided that at least two clusters of laser beams are formed, with all the laser beams of a cluster forming a common vapor capillary. The fact that the laser beams of a common cluster form a common vapor capillary can be achieved by selecting the distance between the images of these laser beams belonging to a common cluster to be less than 1.5 times the diameter of at least one of the images.Laser beams that do not belong to any cluster can be arranged between the clusters in the feed direction. By arranging the laser beams in clusters, particularly good stabilization of the vapor capillaries can be achieved.

[0027] In a further possible embodiment of the invention, it is provided that differences in laser power between the laser beams amount to a maximum of 80 percent, in particular a maximum of 20 percent. In particular, it is provided that the laser beams simultaneously directed onto the welding path have the same laser power. This makes it possible to ensure that the melt solidifies particularly slowly in the wake of the process zone due to the extended melt pool, whereby welding defects can be particularly well avoided and the components can be welded together at a particularly high welding speed. In an alternative possible embodiment of the invention, it is provided that at least two laser beams differ from one another in terms of laser power and / or laser intensity by at least 5 percent, in particular by at least 20 percent.The percentage refers specifically to the smaller laser power or laser intensity. Laser power refers to the total energy emitted by the laser beam per unit of time and is measured in watts (W). It indicates how much energy the laser beam generates overall. Laser intensity, on the other hand, describes the energy per unit area and is measured in watts per square meter (W / m). 2). It indicates how concentrated the laser energy is on a specific area. The laser intensity can therefore vary depending on how the laser beam is focused or distributed. It is possible for two of the laser beams to differ in their laser power but not in their laser intensity. Alternatively, it is possible for the two laser beams to differ in their laser intensity but not in their laser power. Furthermore, it is possible for the two laser beams to differ in both their laser power and their laser intensity.By adjusting the laser power and / or laser intensity of at least two of the laser beams differently, a particularly low temperature gradient in the molten pool, a low susceptibility to cracking of the produced weld seam, a smooth molten pool flow in the molten pool, particularly little spatter on the components, particularly few pores in the weld seam, and a homogeneous weld penetration depth can be achieved. By adjusting the laser power and / or laser intensity of at least two of the laser beams differently, the melt solidifies particularly slowly in the downstream part of the process zone, as the molten pool is extended, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0028] When laser beams arranged directly behind one another in the feed direction have the same laser power, the melt pool heats up in the opposite direction to the feed direction, increasing the capillary depth of the vapor capillaries. This can lead to an unfavorable vapor capillary geometry and resulting melt pool flow. Multiple laser beams arranged in a row with the same laser power can lead to instabilities in the individual vapor capillaries, as the irradiated intensity in the leading and / or trailing laser beams can be too high.

[0029] In this context, it can be provided that at least two laser beams, which are arranged directly one behind the other in the feed direction, differ from each other in terms of laser power and / or laser intensity by at least 5 percent, in particular by at least 20 percent. In other words, it is provided that no further laser beam is arranged between the laser beams, which differ from each other in terms of laser power and / or laser intensity by at least 5 percent, in particular by at least 20 percent, in the feed direction. This allows a melt pool flow to be adjusted particularly precisely.

[0030] In this context, it can further be provided that, of at least two laser beams arranged directly one behind the other along the feed direction, a second laser beam, which trails the first of the two laser beams in the feed direction, has a higher laser power and / or laser intensity than the first laser beam. This ensures that the energy input into the melt pool increases significantly when first the first laser beam and subsequently the second laser beam are moved over the component surface of at least one of the components.

[0031] In this context, it can be provided, in particular, that each laser beam has a higher laser power and / or laser intensity than the laser beam immediately preceding it in the feed direction. In other words, the laser power and / or laser intensity of a respective laser beam are higher the further back the respective laser beam is arranged in the row of laser beams arranged one behind the other in the feed direction. The laser power and / or laser intensity of the respective laser beams arranged in series can, for example, continuously increase counter to the feed direction or converge towards a maximum counter to the feed direction. This enables a targeted widening or tapering of the melt pool.

[0032] Alternatively, it can be provided that at least two of the rearmost laser beams in the feed direction have a laser power and / or laser intensity that is equal to one another and higher than the laser power and / or laser intensity of the remaining laser beams of the laser beams arranged in a row in the feed direction. In other words, the laser power and / or laser intensity of the laser beams can form a plateau towards the rear end of the row—and thus opposite to the feed direction. In this case, it is particularly provided that the laser power and / or laser intensity of the remaining laser beams drops towards the front end of the row of laser beams in the feed direction.For the laser beams that do not have the same laser power and / or laser intensity as the laser beam that is arranged at the rear of the row in the feed direction, the laser power and / or laser intensity is higher than the laser power and / or laser intensity of the laser beams that are moving forward in the feed direction.

[0033] In a further possible embodiment of the invention, it is provided that of at least two laser beams arranged directly one behind the other along the feed direction, a second laser beam, which follows the first laser beam in the feed direction, has a lower laser power and / or laser intensity than the first laser beam. This makes it possible to precisely adjust the temperature of the molten pool, in particular preventing further heating of the molten pool. The decreasing laser power and / or laser intensity within the row of laser beams opposite to the feed direction enables a particularly high degree of efficiency of the welding process. Thus, particularly little energy is required to weld the at least two components.

[0034] In this context, it can be provided, in particular, that each laser beam has a lower laser power and / or laser intensity than the laser beam immediately preceding it in the feed direction. Thus, the further back the respective laser beam is positioned in the row of multiple laser beams, the lower its laser power and / or laser intensity. This can ensure that the capillary depth of the resulting vapor capillaries is the same for all laser beams or decreases in the row of laser beams opposite the feed direction.

[0035] In a further possible embodiment of the invention, one of the laser beams has a higher laser power and / or laser intensity than both the laser beam immediately preceding it in the feed direction and the laser beam immediately following it in the feed direction. This laser beam thus represents at least a local maximum in terms of laser power and / or laser intensity compared to the other laser beams.In this context, it can be provided, in particular, that the laser beam which has the higher laser power and / or laser intensity compared to both the laser beam immediately preceding in the feed direction and the laser beam immediately following in the feed direction has the highest laser power and / or laser intensity compared to all other laser beams of the laser beams arranged one behind the other in the feed direction, wherein, starting from this laser beam having the highest laser power and / or laser intensity, the laser powers and / or laser intensities of the other laser beams decrease towards the respective end of the row of laser beams running in the feed direction. In other words, one of the laser beams can represent a global maximum in terms of laser power and / or laser intensity within the row of laser beams arranged one behind the other in the feed direction.This allows a particularly stable welding process to be achieved.

[0036] In a further possible embodiment of the invention, it is provided that the laser power and / or laser intensity of the respective laser beams along the row of laser beams running in the feed direction decreases and then increases again for at least one laser beam every nth laser beam. In other words, it is provided that the laser power and / or the laser intensity alternately increases and decreases along the row of laser beams arranged one behind the other in the feed direction. In this context, it can be provided, in particular, that the laser power and / or laser intensity of the laser beams arranged one behind the other in the row running in the feed direction alternates between a high first level and a second level that is lower than the first level.In other words, the first of the laser beams can have the high first level of laser power and / or laser intensity, and the second of the laser beams can have the lower second level of laser power and / or laser intensity. The laser power and / or laser intensity of all laser beams arranged one after the other in the feed direction can thus, for example, only alternate between the first level and the second level. One or more first laser beams can be followed by one or more second laser beams. In particular, the sequence of first and second laser beams in the series is periodic in the feed direction. This can stabilize the individual vapor capillaries and lengthen the melt pool. As a result, precise welding of the components can be achieved at high welding speeds.Crack formation can be avoided, particularly in the case of aluminum foils overlapping when components are to be welded together. Furthermore, susceptibility to cracking can be kept particularly low due to the resulting, particularly low temperature gradient. Furthermore, a particularly smooth melt pool flow, particularly few spatter and pores, and a homogeneous welding depth can be achieved. In a further possible embodiment of the invention, it is provided that at least two optical images of two of the laser beams on the component surface differ from one another in diameter by at least 5 percent, in particular by at least 20 percent, in particular by a maximum of 1000 percent. The percentage refers in particular to the smaller diameter.With the same laser power of the laser beams providing the respective images, the laser intensity of the respective images on the component surface differs from one another. This stabilizes the individual vapor capillaries and lengthens the molten pool. As a result, precise welding of the components can be achieved at high welding speeds. Cracking, particularly in the case of aluminum foils in the overlap as components to be welded together, can be avoided. Furthermore, susceptibility to cracking can be kept particularly low due to the resulting, particularly low temperature gradient. Furthermore, a particularly smooth molten pool flow, very few spatter and pores, and a homogeneous welding depth can be achieved.

[0037] If the images of all laser beams in a row of laser beams arranged one behind the other in the feed direction were of the same diameter, the vapor capillary sizes would increase in the opposite direction of the feed direction due to the melt pool heating up against the feed direction. This could cause the vapor capillaries of the rear laser beams in the row to coalesce, leading to instabilities in the melt pool, particularly splashes and / or ejections. Furthermore, the same diameters of all laser beams could lead to a regime shift between the formation of one vapor capillary and multiple vapor capillaries.

[0038] In this context, it can be provided, in particular, that at least two images of two of the laser beams, which are arranged directly one behind the other in the feed direction, differ from one another in diameter on the component surface by at least 5 percent, in particular by at least 20 percent, in particular by a maximum of 1000 percent. In other words, images directly adjacent to one another are designed to have different diameters, in particular by at least 5 percent, in particular by at least 20 percent, in particular by a maximum of 1000 percent. This allows for targeted control of the energy input into the melt pool.In this context, it can be provided in particular that of at least two images arranged directly one behind the other along a feed direction, a second image, which follows the first image in the feed direction, has a smaller diameter than the first image. The rear of the two images therefore has the smaller diameter. As a result, the energy input into a point of the molten pool can decrease while the laser beams are moved over this point in the feed direction. In this context, it can be provided in particular that each of the images has a smaller diameter than the image immediately preceding it in the feed direction. If the molten pool heats up opposite to the feed direction, the decreasing diameters of the images can counteract an increase in the vapor capillary sizes, whereby the molten pool can be stabilized.

[0039] In an alternative possible embodiment of the invention, it is provided that of at least two images arranged directly one behind the other along a feed direction, a second image, which follows the first image in the feed direction, has a larger diameter than the first image. This makes it possible to specifically increase the energy input into the molten pool. In this context, it can be provided in particular that each of the images has a larger diameter than the image immediately preceding it in the feed direction. The further back the respective image is arranged in the row of images arranged one behind the other in the feed direction, the larger the diameter of the respective image. This makes it possible to ensure that the leading, smaller images have a preheating and cleaning effect, as a result of which welding defects, such as nicks, are eliminated.Pores, splashes and ejections can be reduced.

[0040] In a further possible embodiment of the invention, one of the images has a larger diameter than both the image immediately preceding it in the feed direction and the image immediately following it in the feed direction. This image thus represents at least a local maximum with respect to the diameter.In this context, it can be provided in particular that the image which has the larger diameter compared to both the image immediately preceding in the feed direction and the image immediately following in the feed direction has the largest diameter compared to all other images of the laser beams arranged one behind the other in the feed direction, wherein starting from this image having the largest diameter, the diameters of the other images decrease towards the respective end of the row of laser beams running in the feed direction. In other words, one of the images can represent a global maximum of all images arranged in a row in the feed direction with regard to the diameter. In particular, the diameters of the images can decrease continuously from the global maximum towards the respective ends of the row.This allows a particularly low temperature gradient to be achieved, starting from this map representing the global maximum, both forward and backward along the feed direction. This particularly low temperature gradient in both directions makes it possible to minimize crack susceptibility. Furthermore, a melt pool with favorable flow properties can be created, which can reduce humping, for example.

[0041] In a further possible embodiment of the invention, it is provided that at least one of the laser beams comprises a core beam and a cladding beam that surrounds the core beam in a ring shape, wherein it is provided in particular that the core beam has at least 20 percent of the total laser power of the respective laser beam. This means that at most 80 percent of the total laser power of the respective laser beam is provided in the cladding beam of the respective laser beam. It can be provided that all laser beams each comprise a core beam and a cladding beam that surrounds the core beam in a ring shape. In this case, it is provided in particular that an image of the cladding beam on the component surface of the at least one component encloses an image of the core beam on the at least one component surface circumferentially, in particular in a ring shape.

[0042] In this context, it can be provided, in particular, that the laser power of the core beam and / or the laser power of the cladding beam is varied periodically, wherein laser power is continuously introduced into at least one of the components by means of this laser beam during welding. In other words, the laser power of the core beam and / or the laser power of the cladding beam can be pulsed or modulated. It can be provided that both the laser power of the core beam and the laser power of the cladding beam are varied periodically, wherein this variation of the respective laser power can be adapted such that at any time, laser power is introduced into at least one of the components either at least by means of the core beam or at least by means of the cladding beam. For example, the core beam and the cladding beam can be pulsed with temporally offset peaks and thus pulsed with a time offset.By periodically varying the laser power of the core beam and / or the cladding beam, the melt pool can be particularly well stabilized.

[0043] In a further possible embodiment of the invention, it is provided that at least two of the laser beams arranged one behind the other in the feed direction have an intensity profile that differs from one another in cross-section. The intensity profile describes the course of the laser intensity within the cross-section of the respective laser beam. The respective intensity profiles can be Gaussian, annular, or top-hat-shaped, or a combination of these basic shapes. The fact that the laser beams have an intensity profile that differs from one another in cross-section means that these laser beams differ in terms of the shape of their respective intensity profile, for example one of the laser beams has a Gaussian intensity profile and the other laser beam has an annular intensity profile.By using different intensity profiles for at least two of the laser beams arranged one behind the other in the feed direction, the melt pool and the vapor capillaries can be stabilized. Furthermore, humping, spatter, porosity, and weld collapse can be avoided. Furthermore, the feed rate can be increased without causing weld defects by lengthening the melt pool and stabilizing the individual vapor capillaries.

[0044] In particular, it can be provided that the intensity profile of each laser beam has a Gaussian core region and an annular region enclosing the core region. This can achieve particularly good stabilization of the vapor capillaries. Such laser beams can be provided in particular by superimposing two partial laser beams with congruent optical axes and different beam diameters. In particular, it is provided that the power component in the core region amounts to at least 20 percent of the total intensity of this laser beam. In this context, it can be provided in particular that the intensity distribution between the core region and the annular region of a first laser beam differs from the intensity distribution between the core region and the annular region of a second laser beam of the laser beams arranged one behind the other in the feed direction by at least 5 percent.In other words, the intensity distribution between the ring region and the core region differs significantly between at least the two laser beams, namely by at least 5 percent. This allows the melt pool and the at least one vapor capillary to be particularly well stabilized.

[0045] In this context, it can be provided, in particular, that the proportion of the ring region in the total intensity of a respective laser beam is greater than that of a laser beam directly advancing in the feed direction. In other words, it is provided that the proportion of the ring region in the total intensity for the respective laser beams increases in the direction opposite to the feed direction for the laser beams arranged in series. This can achieve a broadening of the melt pool and a stabilization of the respective vapor capillaries that are formed.

[0046] Alternatively, it can be provided that the proportion of the ring region in the total intensity of a respective laser beam is smaller than that of a laser beam immediately preceding in the feed direction. In other words, it is provided that the proportion of the ring region in the total intensity for the respective laser beams decreases in the direction opposite to the feed direction for the laser beams arranged in series. In other words, the proportion of the ring region in the total intensity of a respective laser beam is larger than that of a laser beam immediately following along the feed direction. This can achieve a broadening of the melt pool and a stabilization of the respective vapor capillaries that are formed.

[0047] Furthermore, alternatively, it can be provided that one of the laser beams has a higher proportion of the ring region in the total intensity of this laser beam compared to both the laser beam immediately preceding it in the feed direction and the laser beam immediately following it in the feed direction. With regard to the proportion of the ring region's intensity in the total intensity, this laser beam thus represents at least a local maximum.In this context, it can be provided, in particular, that the laser beam which, compared to both the laser beam immediately preceding in the feed direction and the laser beam immediately following in the feed direction, has the higher proportion of the ring region in the total intensity of this laser beam, compared to all other laser beams arranged one behind the other in the feed direction, has the highest proportion of the total intensity in the ring region, and starting from this laser beam having the highest proportion of the total intensity in the ring region, the proportion of the ring region in the total intensity of the other laser beams decreases towards the respective end of the row of laser beams running in the feed direction. In other words, this laser beam represents not just a local but a global maximum in the row of laser beams arranged one behind the other in the feed direction.The more additional laser beams are arranged in the feed direction between the laser beam with the highest proportion of the ring region in the total intensity and the respective laser beam under consideration, the smaller the proportion of the ring region in the total intensity of the laser beam under consideration. This maximum in terms of the proportion of the ring region in the total intensity for one of the laser beams that is not located at the very front or very back in the row of laser beams can achieve a broadening of the melt pool and a stabilization of the resulting vapor capillaries.

[0048] In a further possible embodiment of the invention, at least two laser beams are arranged next to one another in a direction running obliquely or perpendicular to the feed direction. In particular, this direction, in which the at least two laser beams are arranged next to one another, runs parallel to the component surface. In other words, several laser beams arranged one behind the other in the feed direction are directed onto the component surface, as well as at least one further laser beam which is not arranged in this row and is arranged next to one of the laser beams in the row in a direction running perpendicular to the feed direction. This makes it possible to create a parallelization of several welding paths, whereby particularly high productivity can be achieved.Alternatively or additionally, a particularly wide weld seam can be created by the multiple laser beams arranged next to one another, which are not arranged in the feed direction but in a direction running obliquely or perpendicular to the feed direction.

[0049] If the laser beams are arranged along a single line running in the feed direction, only one weld path can be created at a time. The width of this weld path in a direction perpendicular to the feed direction and parallel to the component surface is then limited by the diameter of the respective laser beam images on the component surface. The focal position bandwidth is limited by the Rayleigh length.

[0050] In a further possible embodiment of the invention, it is provided that a focus position in a direction running perpendicular to the component surface of at least two of the laser beams differs from one another, in particular by more than 5 percent of the Rayleigh length of one of the laser beams. The Rayleigh length is the distance along the optical axis that a laser beam needs until its cross-sectional area doubles, starting from the beam waist or the focus. In this context, it can be provided, in particular, that the laser beams differing in focus position are arranged next to one another in the feed direction or in a direction running perpendicular to the feed direction and parallel to the component surface.The differently selected focus positions of the laser beams enable all of the laser beams to be provided with a particularly high focus position tolerance, since different laser beams with different focus positions cover a particularly wide focus position range.

[0051] In this context, it can be provided, in particular, that all laser beams arranged in a row in the feed direction have different focal positions relative to one another. In particular, the respective laser beams each have a lower focal position than the laser beam immediately ahead in the feed direction. In other words, the focal position of the respective laser beams within a row decreases toward the rear end of the row. For example, it can be provided that the further forward the respective laser beam is arranged within the row with respect to the feed direction, the greater the distance between its focal position and the component surface.

[0052] In a further possible embodiment of the invention, it is provided that the images of respective laser beams of a first row running in the feed direction and a second row running parallel thereto in the feed direction are arranged offset from one another in the feed direction, in particular by at least 10 percent of the diameter of one of the images. In other words, at least two rows of laser beams are aligned with the component surface. Each of the rows of laser beams runs in the feed direction. Consequently, the at least two rows of laser beams run parallel to one another. At least one of the rows is shifted in the feed direction compared to the other row. The laser beams of the two rows are therefore not arranged next to one another on respective axes running perpendicular to the feed direction, but are offset from one another in the feed direction.As a result, the distance between the two adjacent rows in a direction perpendicular to the feed direction and parallel to the component surface is shorter than the distance between the first image of a laser beam in the first row and the second image of a laser beam in the second row closest to the first image. This offset of the laser beams of the two rows relative to each other allows for a particularly high density of images on the component surface while simultaneously maintaining a particularly large distance between the images.

[0053] In a further possible embodiment of the invention, the laser beams are arranged in a first row running in the feed direction and in a second row running parallel thereto in the feed direction, each of the rows comprising at least two laser beams and one of the rows comprising more laser beams than the other. In other words, a main row and at least one secondary row of laser beams arranged one behind the other in the feed direction are provided. The at least one secondary row of laser beams enables lateral heating of the component surface adjacent to the region of the component surface that is heated, in particular welded, by means of the main row. This lateral heating leads to a particularly low temperature gradient in at least one of the components to be welded and, as a result, to particularly little humping, cracks, or inhomogeneities in the molten pool.

[0054] In this context, it can be provided, in particular, that the laser beams are arranged in a first row running in the feed direction and in a second row running parallel thereto in the feed direction, each of the rows comprises at least two laser beams, and respective straight lines running through the centers of a respective row in a direction perpendicular to the feed direction and parallel to the component surface are spaced from one another by at least three times, in particular at least five times, the maximum diameter of the images. This ensures that each row forms a separate molten pool. As a result, parallel weld seams are produced simultaneously by means of the multiple rows, whereby particularly high productivity can be achieved.Alternatively, it can be provided that the laser beams are arranged in a first row running in the feed direction and in a second row running parallel thereto in the feed direction, each of the rows comprises at least two laser beams and respective straight lines running through the centers of a respective row in a direction perpendicular to the feed direction and parallel to the component surface are spaced from one another by less than three times the maximum diameter of the images. As a result, the molten pools formed by the respective rows of laser beams overlap. This makes it possible to produce a weld seam with a particularly large width in a direction perpendicular to the feed direction and parallel to the component surface.

[0055] The invention further relates to a laser welding device for welding at least two components along a welding path running on a component surface of at least one of the components. The laser welding device is configured to align at least three laser beams, in particular five to 30 laser beams, simultaneously one after the other onto the welding path and to move them over the component surface at the same feed rate in a welding direction running along the welding path. As a result, the welding path is traversed one after the other by all laser beams, at least over a length range. While the laser beams are moving in the welding direction, laser power is introduced into at least one of the components by means of each of the laser beams. In particular, the laser welding device is configured to arrange the laser beams such that the laser beams generate a common, continuous melt pool.The laser welding device is particularly designed to carry out a method as has already been described in connection with the method according to the invention for welding at least two components.

[0056] Further features of the invention can be derived from the following description of the figures and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0057] The drawings show: Fig. 1 a schematic plan view of a component surface of a component onto which several laser beams are directed;

[0058] Fig. 2a, b a perspective sectional view of the component onto which several laser beams are aligned one behind the other in the feed direction, wherein a distance between the respective laser beams decreases towards the front in the feed direction, and a diagram in which the respective distances are plotted;

[0059] Fig. 3a, b a perspective sectional view of the component onto which several laser beams are aligned one behind the other in the feed direction, wherein one of the distances between the respective laser beams represents a local maximum of the distances, and a diagram in which the respective distances are plotted;

[0060] Fig. 4a, b a perspective sectional view of the component onto which several laser beams are aligned one behind the other in the feed direction, wherein a distance between the respective laser beams increases forward in the feed direction, and a diagram in which the respective distances are plotted;

[0061] Fig. 5a, b a perspective sectional view of the component onto which several laser beams are aligned one behind the other in the feed direction, wherein the distances between the respective laser beams form at least two clusters, and a diagram in which the respective distances are entered;

[0062] Fig. 6 is a diagram for respective laser intensities of the plurality of laser beams arranged one behind the other in the feed direction and directed onto the component surface of the component, wherein the laser intensity of the respective laser beams decreases forward in the feed direction;

[0063] Fig. 7 is a diagram for respective laser intensities of the plurality of laser beams arranged one behind the other in the feed direction and directed onto the component surface of the component, wherein the laser intensities of the rearmost laser beams in the feed direction form a plateau and, starting from this plateau, the laser intensities of the further laser beams decrease forward in the feed direction;

[0064] Fig. 8 is a diagram for respective laser intensities of the plurality of laser beams arranged one behind the other in the feed direction and directed onto the component surface of the component, wherein the laser intensity of the respective laser beams increases forward in the feed direction;

[0065] Fig. 9 is a diagram for respective laser intensities of the plurality of laser beams arranged one behind the other in the feed direction and directed onto the component surface of the component, wherein the laser intensity of the respective laser beams alternates in the feed direction between a first, higher level and a second, lower level;

[0066] Fig. 10 is a diagram for respective laser intensities of the plurality of laser beams arranged one behind the other in the feed direction and directed onto the component surface of the component, wherein the laser intensity of a middle one of the laser beams represents a local maximum;

[0067] Fig. 11a, b a schematic plan view of the component surface of the component onto which several laser beams are aligned one after the other in the feed direction, wherein a diameter of respective images of the laser beams increases forward in the feed direction, and a diagram in which the respective diameters of the images are plotted;

[0068] Fig. 12a, b a schematic plan view of the component surface of the component onto which several laser beams are aligned one after the other in the feed direction, wherein a diameter of a middle one of the images of the laser beams represents a local maximum, and a diagram in which the respective diameters of the images are plotted;

[0069] Fig. 13a, b a schematic plan view of the component surface of the component onto which several laser beams are aligned one after the other in the feed direction, wherein a diameter of respective images of the laser beams decreases forward in the feed direction, and a diagram in which the respective diameters of the images are plotted;

[0070] Fig. 14 a schematic representation of several basic shapes and several combinations of possible intensity profiles of the laser beams in cross section;

[0071] Fig. 15 is a diagram for respective intensity profiles of the plurality of laser beams arranged one behind the other in the feed direction and directed onto the component surface of the component, wherein the intensity profiles of the respective laser beams each comprise a Gaussian core region and a ring region surrounding the core region in a ring shape, wherein the proportion of the ring region in the total intensity of the respective laser beam decreases forward in the feed direction;

[0072] Fig. 16 is a diagram for respective intensity profiles of the plurality of laser beams arranged one behind the other in the feed direction and directed onto the component surface of the component, wherein the intensity profiles of the respective laser beams each comprise a Gaussian core region and a ring region surrounding the core region in a ring shape, wherein the proportion of the ring region to the total intensity of the laser beam represents a local maximum for a middle one of the laser beams;

[0073] Fig. 17 is a diagram for respective intensity profiles of the plurality of laser beams arranged one behind the other in the feed direction and directed onto the component surface of the component, wherein the intensity profiles of the respective laser beams each comprise a Gaussian core region and a ring region surrounding the core region in a ring shape, wherein the proportion of the ring region in the total intensity of the respective laser beam increases forward in the feed direction;

[0074] Fig. 18 is a schematic plan view of the component surface of the component onto which several laser beams are aligned one behind the other in respective rows running in the feed direction, wherein a lateral distance between the rows is so large that each of the rows forms a separate melt pool;

[0075] Fig. 19 is a schematic plan view of the component surface of the component onto which several laser beams are aligned one behind the other in respective rows running in the feed direction, wherein a lateral distance between the rows is so small that all rows form a common melt pool;

[0076] Fig. 20 is a schematic sectional view of the component onto which several laser beams are aligned one after the other in the feed direction, the focus positions of the laser beams within a row increasing forward in the feed direction;

[0077] Fig. 21 is a schematic sectional view of the component onto which a plurality of laser beams are aligned one behind the other in at least two rows in the feed direction, wherein the focus positions of the laser beams within a row increase forward in the feed direction and the focus positions of the at least two rows differ from one another at least with respect to one laser beam;

[0078] Fig. 22 is a schematic plan view of the component surface of the component onto which several laser beams are aligned in respective rows extending in the feed direction, wherein at least two of the rows have a relative offset to each other in the feed direction; and

[0079] Fig. 23 is a schematic plan view of the component surface of the component onto which several laser beams are aligned one behind the other in respective rows running in the feed direction, wherein the respective rows comprise different numbers of laser beams.

[0080] In the figures, identical and functionally identical elements are provided with the same reference numerals.

[0081] The drawing shows in Fig. 1 a plan view of a component surface 10 of a component 12. In particular, two components 12 are stacked on top of one another in a stacking direction running into the image plane in Fig. 1, and are to be welded together. The components 12 are in particular respective battery components, in particular battery components for a vehicle battery of a motor vehicle. For example, at least one of the battery components can be a cell contact system. The components 12 stacked on top of one another in the stacking direction and to be welded together (lap joint) can be made of the same material or of different materials. Alternatively, butt joints, T-joints or fillet welds can also be produced. The invention is particularly advantageous if the weld path does not have a change in direction.Alternatively, at least one of the components 12 is a component of a bipolar plate or a bipolar plate, particularly for a fuel cell or an electrolyzer. In addition to battery components and fuel cells, all metallic materials, particularly those based on iron, aluminum, or copper, can generally be welded together. Materials of the same or different types can be welded together. This also applies to the welding of pipe and profile applications, components from the aerospace, energy, automotive, or medical technology sectors.

[0082] The two components 12 can be welded together, in particular by means of a laser welding device. The laser welding device is configured to provide a plurality of laser beams 14. To weld the components 12, at least three laser beams 14, in this case more than three laser beams 14, are directed simultaneously one after the other onto a welding path 16. In the embodiment shown in Fig. 1, it is provided that laser power is introduced into at least one of the components 12 simultaneously with all of the laser beams 14 directed simultaneously onto the welding path 16. It is further provided that, during the welding of the components 12, laser power is introduced into at least one of the components 12 continuously by means of at least one of the laser beams 14, in particular by means of all of the laser beams 14.The laser beams 14 can be operated in particular in a continuous operation, which can also be referred to as so-called continuous wave operation.

[0083] By directing the laser beams 14 onto the welding path 16, a molten pool of melt is created, whereby, as the melt solidifies, a weld seam 18 is formed, via which the components 12 are held together. In one possible embodiment, it is provided that all laser beams 14 are arranged one behind the other in a straight line on the welding path 16. To weld the components 12 together, it is provided that all laser beams 14 are moved at the same feed rate in the welding direction 20 along the welding path 16. As a result, the welding path 16 is irradiated successively by all laser beams 14, at least for the most part, at each of its points.In this embodiment, the laser beams 14 arranged one behind the other in the longitudinal direction of the weld path 16 allow all laser beams 14 to create only a single, elongated molten pool, allowing the melt to solidify particularly slowly in the downstream part of a process zone. This allows welding defects such as humping to be particularly reliably avoided, even at high welding speeds.

[0084] In Fig. 1, images 22 of the respective laser beams 14 caused by the laser beams 14 on the component surface 10 of the component 12 can be seen particularly well. In this case, a distance a between two images 22 directly adjacent to one another in the welding direction 20 extends from a center point of one of the images 22 under consideration to the center point of the other image 22 under consideration, as can be seen particularly well in Fig. 1. In the present embodiment shown in Fig. 1, it is provided that the distance a between the centers of the respective images 22 directly adjacent to one another in the welding direction 20 is greater than a diameter d of the respective images 22. It is further provided that all images 22 have at least substantially the same diameter d. Furthermore, in the embodiment shown in Fig.1, it is provided that all images 22 have an at least substantially equal distance a from the next further image 22. In the embodiment shown in Fig. 1, it is further provided that the distance a between the centers of respective images 22 directly adjacent to one another in the welding direction 20 is greater than at least 20 percent, in particular greater than at least 25 percent of a width 28 of the weld seam 18 produced by welding, said width running perpendicular to the welding direction 20 on the component surface 10. It is provided that the parameters for the laser beams 14 are set such that at least two of the laser beams 14 each generate a vapor capillary. In particular, it is provided that the parameters for the laser beams 14 are set such that all laser beams 14 each generate a vapor capillary.In the present embodiment shown in Fig. 1, it is further provided that differences in laser power between the respective laser beams 14 amount to a maximum of 80 percent, in particular a maximum of 20 percent. Furthermore, it is provided that all laser beams 14 have the same power.

[0085] In the embodiment shown in Fig. 1, the beam diameters of all laser beams 14 are identical in a common plane perpendicular to a beam direction. This means that all images 22 have at least substantially the same diameter d. This allows a particularly slim weld seam 18 to be created, and particularly little heat input is required for welding the components 12. Alternatively, it is possible for the largest individual beam diameter of the laser beams 14 to be a maximum of ten times larger than the smallest individual beam diameter of the laser beams 14.

[0086] It is possible for at least one of the laser beams 14, in particular all of the laser beams 14, to each comprise a core beam and a cladding beam that surrounds the core beam in a ring. To generate the respective laser beams 14 with the core beam and the cladding beam, two partial laser beams with congruent optical axes and different beam diameters can be superimposed for each laser beam 14. By providing the respective laser beams 14 with the core beam and the cladding beam, the respective vapor capillaries generated can be particularly well stabilized. In particular, it is provided that the power component in the core beam amounts to at least 80 percent of the total power of the respective laser beam 14.The laser beams 14 comprising the respective core beam and the cladding beam can be provided by means of a respective optical fiber cable with two-in-one technology, i.e. with ring fiber and core fiber, wherein a two-in-one main beam can be divided into several individual beams.

[0087] As a laser welding device, a CW laser beam source with optionally modulated laser power or pulsed laser power can be provided, with a modulation amplitude of no more than 10 percent of a maximum power. The described method can be used in particular for bipolar plates of a fuel cell or an electrolyzer, since tight weld seams can be created with particularly low heat input, and particularly high productivity can be achieved. Alternatively, the method can be used for welding two battery components, in particular a cell contact made of at least two different materials, since the method enables welding with particularly few intermetallic phases and a weld seam with particularly high strength can be created with particularly low heat input.Furthermore, alternatively, the method can be used for welding a foil stack with at least one foil comprising aluminum. The method enables slim weld seams 18 to be created with short interaction times, whereby the risk of cracking can be particularly effectively reduced. The method therefore enables welding to be carried out at particularly high welding speeds, whereby particularly little heat input is required. Furthermore, the precise welding achieves particularly good gas tightness. In the case of mixed joints, the formation of intermetallic phases can be particularly effectively limited. Furthermore, the method enables a reduction in cracking, particularly in the case of foils comprising aluminum in the overlap.

[0088] The method can thus be used for laser welding thin metal foils of a single type, whether iron-based, aluminum-based, or copper-based, or for mixed joints. In particular, the sheet thickness of at least one joining partner and thus at least one of the components 12 is in the range of seven micrometers to 1,000 micrometers, in particular in the range of seven micrometers to 20 micrometers for electrode foils and 75 micrometers to 500 micrometers for arresters. Single-mode lasers with 100 to 3,000 watts per beam source or multi-mode lasers with 1,000 to 24,000 watts per beam source can be used as the laser beam source for generating the laser beams 14. In particular, the total power at the components 12 for all laser beams 14 is 1,000 to 6,000 watts. The laser power per laser beam 14 is in the range of 10 to 8,000 watts, in particular in the range of 50 to 700 watts.The laser welding device can comprise at least one optical element for splitting at least one laser input beam into a plurality of individual beams, for example a multifocal lens or an optical wedge plate, in particular a diffractive optical element or a refractive optical element. It is possible for the laser beams 14 to be provided by means of a laser beam source and an optical system, or by means of at least two laser beam sources and an optical system, or by means of a laser beam source and at least two optical systems, or by means of at least two laser beam sources and at least two optical systems. A beam parameter product of the laser beams 14 is in particular in the range from 0.38 to 16 mm*mrad, in particular in the range from 0.4 to 0.6 mm*mrad for a single-mode laser or in the range from two to four mm*mrad for a multi-mode laser.The diameter d of the respective images 22 is in particular in the range from ten micrometers to 300 micrometers, in particular in the range from 30 micrometers to 50 micrometers for a single-mode laser and in the range from 50 micrometers to 170 micrometers for a multi-mode laser. In particular, all images 22 of the laser beams 14 have a diameter d in the range of 0.1 to ten times, in particular the same diameter d as, the foremost laser beam 14 with respect to the welding direction 20.

[0089] In the present embodiment shown in Fig. 1, the laser beams 14 are arranged in a line, in particular without lateral offset. If at least one of the laser beams 14 is arranged with a lateral offset, then this lateral offset is less than or equal to the maximum beam diameter of all images 22 of the laser beams 14. It is possible for the laser welding device to have an infrared laser with a wavelength in the range of 800 nanometers to 1,200 nanometers, in particular a wavelength of 1,030 nanometers or 1,070 nanometers. Alternatively or additionally, the laser welding device can have a VIS laser with a wavelength in the range of 400 to 450 nanometers for blue light and / or a wavelength in the range of 515 nanometers for green light. It would also be possible for the individual spots to have different wavelengths, but preferably all the same wavelength.

[0090] The feed rate in this case is in the range from 100 millimeters per second to 10,000 millimeters per second, in particular in the range from 300 millimeters per second to 4,000 millimeters per second. The laser welding device can, in particular, have a PFO33-2 scanner optics with an imaging ratio of 1:1 to 5:1, in particular 1.5:1 to 2:1, as the scanner optics. Alternatively or additionally, the laser welding device can have a BEO flying optics with an imaging ratio of 1:1 to 5:1, in particular 1.5:1 to 2:1.

[0091] In Fig. 2a, a perspective sectional view of the component 12 is shown, onto which several laser beams 14 are aligned one behind the other in the feed direction V - which corresponds to the welding direction 20 - with a distance a nbetween the respective laser beams 14 decreases forward in the feed direction V. Furthermore, Fig. 2b shows a diagram in which the respective distances a n from Fig. 2a. The ordinate represents the percentage difference between the respective distances a n applied.

[0092] In Fig. 3a, a perspective sectional view of the component 12 is shown, onto which several laser beams 14 are aligned one after the other in the feed direction V, wherein one of the distances as between the respective laser beams 14 is a local maximum of the distances a n Furthermore, Fig. 3b shows a corresponding diagram in which the respective distances a n from Fig. 3a. The ordinate represents the percentage difference between the respective distances a n and a reference distance.

[0093] In Fig. 4a, a perspective sectional view of the component 12 is shown, onto which several laser beams 14 are aligned one behind the other in the feed direction V, wherein a distance a n between the respective laser beams 14 increases forward in the feed direction V. Furthermore, Fig. 4b shows an associated diagram in which the respective distances a n from Fig. 4a. The ordinate represents the percentage difference between the respective distances a n and a reference distance.

[0094] In Fig. 5a, a perspective sectional view of the component 12 is shown, onto which several laser beams 14 are aligned one behind the other in the feed direction V, wherein the distances a n between the respective laser beams 14 at least two clusters C nIt is thus provided that the laser beams 14 arranged in a row in the feed direction V form at least two clusters C n form, wherein the distances between the images of laser beams 14 arranged directly one behind the other in the feed direction V of a common cluster C n less than 1.5 times the diameter d of the image of one of the laser beams 14 of cluster C n A cluster C n comprises at least two laser beams 14. Each cluster C of laser beams 14 generates a separate vapor capillary. Furthermore, Fig. 5b shows an associated diagram in which the respective distances a n from Fig. 5a. The ordinate represents the percentage difference between the respective distances a n and a reference distance.

[0095] The embodiments described in connection with Figs. 2a to 5b are based on the knowledge that instabilities can occur when several laser beams 14 are arranged in a row at equal distances, since trailing vapor capillaries can coalesce and cause turbulent lard bath dynamics.

[0096] A specific example of these embodiments is described below: In this example, laser welding of metallic components based on iron, aluminum, or copper, or mixed joints, takes place, wherein the sheet thickness of a joining partner is in the range of 7 pm - 20 mm, in particular in the range of 75 pm - 500 pm for foils or in the range of 500 pm - 5 mm for sheets, e.g., for battery production. Laser beam sources are single-mode lasers with 100-3000 W per beam source or multi-mode lasers with 1000-100,000 W per beam source; in particular, the total power at the workpiece is 50-30,000 W per MultiSpot line—which refers to a series of laser beams 14 arranged one behind the other in the feed direction V. The laser power per laser beam 14 is in the range 10-10000 W. It is intended that at least one optical element is used to split at least one input laser beam into several individual beams, e.g.The individual beams are generated by diffractive beam splitters, which generate diffraction orders whose power components (weightings) are controlled by the grating geometry, in particular by the phase modulation of a periodically extended unit cell. Possible embodiments include phase modulation by optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence by nanogratings in glasses or polymers, additively manufactured (2PP) optics, etc.), or phase modulation by one or more microlens arrays connected in series. The phase modulation can be imposed on an illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, 8-level DOEs).

[0097] Multiple laser beams from one laser beam source and one optical system can be used. Alternatively, multiple laser beams from at least two laser beam sources and one optical system can be used. Alternatively, multiple laser beams from one laser beam source and at least two optical systems can be used. Alternatively, multiple laser beams from at least two laser beam sources and at least two optical systems can be superimposed.

[0098] The beam parameter product is in the range of 0.38–30 mm*mrad, in particular in the range of 0.4–0.6 mm*mrad (single-mode) or in the range of 2–4 mm*mrad (multi-mode). The diameter d1 of the first image 22 of the series of laser beams 14 on the component surface 10 is in the range of 10 pm–3000 pm, in particular 30 pm–50 pm (single-mode) and 50 pm–1500 pm (multi-mode). A linear arrangement of the images 22 is provided, preferably without lateral offset, alternatively with a lateral offset of at most d ma x (d ma x is the maximum diameter of the largest image 22 on the component surface 10). The distance a between the images 22 is preferably at least d max. Each intensity profile of an individual laser beam can consist of a core and a ring component, with the intensity being higher in the core than in the ring. In particular, an infrared laser with a wavelength in the range 800-1200 nm, in particular 1030 nm or 1070 nm or 1080 nm is used. Alternatively, a VIS laser is used, in particular a VIS laser with a wavelength of 400-450 nm (blue) and 515 nm (green). The implemented feed rate is in the range 50 mm / s to 10,000 mm / s, in particular 300-4,000 mm / s. PFO33-2 with an imaging ratio of 1:1 to 5:1, in particular 1.5:1 to 2:1, is used as scanner optics. Alternatively, a BEO flying optics with the same imaging ratios is used.

[0099] By using at least three laser beams 14, in particular 3 to 50 laser beams 14, arranged in a row in the feed direction V, the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is extended, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0100] In particular, the distance a between the figures 22 of the laser beams 14 is at least as large as 50 percent of the diameter d of the figures 22. This leads to an overall longer melt pool and thus to higher welding speeds due to particularly little humping.

[0101] It is intended that at least one of the laser beams 14 does not generate a vapor capillary (heat conduction welding) and at least one of the laser beams 14 generates a vapor capillary (deep penetration welding). Furthermore, it is intended that a cw laser beam source with optionally modulated laser power or a pulsed laser beam source is used, wherein the modulation amplitude is at least 10 percent of the maximum power. This ensures that the melt solidifies particularly slowly in the downstream part of the process zone, as the melt pool is lengthened, thereby avoiding welding defects. As a result, a particularly high welding speed can be achieved. When used for bipolar plates of a fuel cell or an electrolyzer, tight seams, low heat input and high productivity can be achieved. When used for welding two battery components, e.g.When used for housings, or when used in pipe and profile applications, particularly high welding speeds and particularly high process stability can be achieved. When used for aluminum foil stacks (for batteries), slim seams with short interaction times can be created, which tend to reduce cracking.

[0102] The beam diameters of the laser beams 14 are preferably identical. Alternatively, the largest individual beam diameter can be a maximum of ten times larger than the smallest beam diameter. This allows for the creation of slim seams that allow for particularly low heat input.

[0103] In particular, it is provided that each laser beam 14 consists of a core region and a ring region, in particular by superimposing two beams with preferably congruent optical axes and different beam diameters. In particular, the power component in the core beam is at least 20% of the total power of the respective laser beam 14.

[0104] To stabilize the vapor capillaries, a fiber optic cable (LCC) with 2-in-1 technology, i.e., a ring fiber and a core fiber, can be used. A 2-in-1 main beam is split into several individual beams. The power in the core portion and / or the ring portion can be modulated or pulsed to stabilize the melt pool. To stabilize the process, the laser beams, each forming a vapor capillary, can be applied in different operating modes, either modulated or pulsed.

[0105] The beam bundle can be generated by a multi-fiber array, whereby each individual beam can be controlled by a laser module.

[0106] The following describes a cost-effective, robust, easy-to-adjust, space-saving, and high-performance solution: Generation of the individual beams by diffractive beam splitters, which generate diffraction orders whose diffraction angles are controlled by the grating geometry, in particular by the phase modulation of a periodically extended unit cell. The different diffraction angles of the diffraction orders are converted by a focusing unit into spatially separated laser beams 14 of a focal plane. The diffraction angles are selected precisely so that the laser beam positions can be freely selected, in particular not equidistantly arranged. Possible embodiments include phase modulation by optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence by nanogratings in glasses or polymers, additively manufactured (2PP) optics, etc.).), or alternatively, phase modulation by one or more microlens arrays connected in series. The phase modulation can be applied to the illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, or 8-level DOEs).

[0107] Figs. 6 to 10 show respective diagrams in which the respective laser intensities are plotted on the ordinate in percent for the plurality of laser beams 14 arranged one behind the other in the feed direction V and directed onto the component surface 10 of the component 12. In the embodiment shown in Fig. 6, the laser intensities of the respective laser beams 14 decrease forward in the feed direction V, in this case continuously.

[0108] Fig. 7 shows an embodiment in which the laser intensities of the rearmost laser beams 14 in the feed direction V form a plateau, wherein, starting from this plateau, the laser intensities of the further laser beams 14 decrease forward in the feed direction V, in this case continuously. In other words, in this case, the four rearmost laser beams 14 in the feed direction V have a laser intensity that is equal to one another, which is higher than the laser intensity of the remaining laser beams 14 of the laser beams 14 arranged in a row in the feed direction.

[0109] In the embodiment shown in Fig. 8, the laser intensities of the respective laser beams 14 increase forward in the feed direction V, in this case continuously.

[0110] Fig. 9 shows an embodiment in which the laser beams 14 arranged in series alternate in terms of their laser intensity in the feed direction between a first, higher level and a second, lower level. In this case, a laser intensity of 100 percent is shown as the first, higher level, and a laser intensity of 20 percent is shown as the second, lower level. In other words, the laser intensity is provided for every second laser beam to be 100 percent and for the respective laser beams arranged in between in the feed direction to be 20 percent.

[0111] Fig. 10 shows an embodiment in which the laser beam 14 designated "Spot 6" represents a local maximum in terms of its laser intensity. Starting from the laser beam "Spot 6," the laser intensities of the other laser beams 14 decrease continuously both in and against the feed direction V toward the respective ends of the row.

[0112] A specific example of these embodiments is described below: In this example, laser welding of metallic components based on iron, aluminum, or copper, or mixed joints, takes place, wherein the sheet thickness of a joining partner is in the range of 7 pm - 20 mm, in particular in the range of 75 pm - 500 pm for foils or in the range of 500 pm - 5 mm for sheets, e.g., for battery production. Laser beam sources are single-mode lasers with 100-3000 W per beam source or multi-mode lasers with 1000-100,000 W per beam source. In particular, the total power at the workpiece is 50-30,000 W per MultiSpot line - which is understood to mean a series of laser beams 14 arranged one behind the other in the feed direction V. The laser power per laser beam 14 is in the range 10-10000 W. It is intended that at least one optical element is used to split at least one input laser beam into several individual beams, e.g.The individual beams are generated by diffractive beam splitters, which generate diffraction orders whose power components (weightings) are controlled by the grating geometry, in particular by the phase modulation of a periodically extended unit cell. Possible embodiments include phase modulation by optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence by nanogratings in glasses or polymers, additively manufactured (2PP) optics, etc.), or phase modulation by one or more microlens arrays connected in series. The phase modulation can be imposed on an illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, 8-level DOEs).

[0113] Multiple laser beams from one laser beam source and one optical system can be used. Alternatively, multiple laser beams from at least two laser beam sources and one optical system can be used. Alternatively, multiple laser beams from one laser beam source and at least two optical systems can be used. Alternatively, multiple laser beams from at least two laser beam sources and at least two optical systems can be superimposed.

[0114] The beam parameter product is in the range of 0.38–30 mm*mrad, in particular in the range of 0.4–0.6 mm*mrad (single-mode) or in the range of 2–4 mm*mrad (multi-mode). The diameter d1 of the first image 22 of the series of laser beams 14 on the component surface 10 is in the range of 10 pm–3000 pm, in particular 30 pm–50 pm (single-mode) and 50 pm–1500 pm (multi-mode). A linear arrangement of the images 22 is provided, preferably without lateral offset, alternatively with a lateral offset of at most d ma x (d ma x is the maximum diameter of the largest image 22 on the component surface 10). The distance a between the images 22 is preferably at least d max. Each intensity profile of an individual laser beam can consist of a core and a ring component, with the intensity being higher in the core than in the ring. In particular, an infrared laser with a wavelength in the range 800-1200 nm, in particular 1030 nm or 1070 nm or 1080 nm is used. Alternatively, a VIS laser is used, in particular a VIS laser with a wavelength of 400-450 nm (blue) and 515 nm (green). The implemented feed rate is in the range 50 mm / s to 10,000 mm / s, in particular 300-4,000 mm / s. PFO33-2 with an imaging ratio of 1:1 to 5:1, in particular 1.5:1 to 2:1, is used as scanner optics. Alternatively, a BEO flying optics with the same imaging ratios is used.

[0115] By using at least three laser beams 14, in particular 3 to 50 laser beams 14, arranged in a row in the feed direction V, the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is extended, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0116] The laser beams are arranged one behind the other in the feed direction, in particular without any lateral offset from one another, alternatively with a lateral offset of at most the maximum diameter of the images 22 on the component surface 10. As a result, the melt solidifies particularly slowly in the downstream part of the process zone, since the melt pool is lengthened, which can prevent welding defects. This makes it possible to achieve particularly high welding speeds. It is intended that a distance a between the images 22 of the laser beams 14 on the component surface 10 corresponds to at least one largest diameter d of the images 22 on the component surface 10. This makes it possible to achieve a particularly long melt pool and, consequently, a particularly high welding speed due to particularly little humping.Furthermore, differences in laser power between the laser beams are intended to be at least 5 percent, which means that the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is lengthened, thus avoiding welding defects. This makes it possible to achieve particularly high welding speeds. If the laser intensity increases continuously against the feed direction, then a targeted widening or narrowing of the melt pool can be set. If the laser intensity increases up to a point and then remains at this level, a particularly stable process can be achieved. Alternatively, the laser intensity can converge to a maximum against the feed direction. If the laser intensity decreases against the feed direction, then the depth of the vapor capillaries can remain constant or decrease against the feed direction.If the laser intensity alternately decreases and then increases again every nth laser beam 14 for at least one laser beam 14, the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is lengthened, thus preventing welding defects. This allows for particularly high welding speeds. If the laser intensities form at least one local maximum, a particularly stable process can be achieved.

[0117] It is intended that at least one of the laser beams 14 does not generate a vapor capillary (heat conduction welding) and at least one of the laser beams 14 generates a vapor capillary (deep penetration welding). Furthermore, it is intended that a continuous wave laser beam source with optionally modulated laser power or a pulsed laser beam source is used, with the modulation amplitude being at least 10 percent of the maximum power. This ensures that the melt solidifies particularly slowly in the downstream part of the process zone, as the melt pool is extended, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0118] When used for bipolar plates in a fuel cell or electrolyzer, tight seams, low heat input, and high productivity can be achieved. When used for welding two battery components, particularly cell contacts made of at least two different materials, it is possible to achieve a very low formation of intermetallic phases, as well as particularly high strength and low heat input. When used for aluminum foil stacks (for batteries) or in pipe and profile applications, slim seams with short interaction times can be created, which tend to reduce cracking.

[0119] Furthermore, this design provides that the distance a between the images 22 of the laser beams 14 corresponds at least to the diameter d of the images 22 on the component surface 10. This stabilizes the vapor capillary and the energy input. Furthermore, a precise penetration depth can be achieved along the entire weld seam, thus achieving a high degree of gas tightness.

[0120] The beam diameters of the laser beams 14 are preferably identical. Alternatively, the largest individual beam diameter can be a maximum of ten times larger than the smallest beam diameter. This allows for the creation of slim seams that allow for particularly low heat input.

[0121] In particular, it is provided that each laser beam 14 consists of a core region and a ring region, in particular by superimposing two beams with preferably congruent optical axes and different beam diameters. In particular, the power component in the core beam is at least 80% of the total power of the respective laser beam 14.

[0122] To stabilize the vapor capillaries, a fiber optic cable (FOC) with 2-in-1 technology, i.e., a ring fiber and a core fiber, can be used. A 2-in-1 main beam is split into several individual beams. The power in the core portion and / or the ring portion can be modulated or pulsed to stabilize the melt pool.

[0123] The following describes a cost-effective, robust, easy-to-adjust, space-saving, and high-performance solution: Generation of the individual beams by diffractive beam splitters that generate diffraction orders whose power components (weightings) are controlled by the grating geometry, in particular by the phase modulation of a periodically extended unit cell. Possible embodiments include phase modulation by optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence by nanogratings in glasses or polymers, additively manufactured (2PP) optics, etc.), or alternatively, phase modulation by one or more microlens arrays connected in series. The phase modulation can be imposed on the illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, 8-level DOEs).

[0124] The beam bundle can be generated by a multi-fiber array, allowing each individual laser beam to be controlled by a laser module. For process stabilization, the laser beams, each forming a vapor capillary, can be modulated or pulsed in different operating modes.

[0125] Fig. 11a shows a schematic plan view of the component surface 10 of the component 12, onto which several laser beams 14 are aligned one after the other in the feed direction V. It can be seen that in this embodiment it is provided that a diameter d nrespective images 22 of the laser beams 14 increases continuously in the feed direction V. The further forward in the row of laser beams 14 a respective laser beam 14 is arranged, the larger the diameter d of its image 22 on the component surface 10. Fig. 11b shows a diagram in which the respective diameters d of the images 22 for the respective laser beams 14 from Fig. 11a are plotted, wherein the respective percentage deviation of the respective diameter d from a reference diameter is plotted on the ordinate.

[0126] Fig. 12a shows a schematic plan view of the component surface 10 of the component 12, onto which several laser beams 14 are aligned one after the other in the feed direction V. It can be seen that in this embodiment it is provided that a diameter d na middle one of the images 22 of the laser beams 14 represents a local maximum. In this case, it is provided that the image 22, which has the larger diameter (de) compared to both the image 22 immediately preceding in the feed direction V and the image 22 immediately following in the feed direction V, has the largest diameter d compared to all other images 22 of the laser beams 14 arranged one after the other in the feed direction V. Starting from this image 22 having the largest diameter (de), the diameters d of the other images 22 decrease towards the respective end of the row of laser beams 14 running in the feed direction V, in this case decrease continuously. Fig. 12b shows a diagram in which the respective diameters d of the images 22 for the respective laser beams 14 from

[0127] Fig. 12a, with the respective percentage deviation of the respective diameter d from a reference diameter being plotted on the ordinate.

[0128] Fig. 13a shows a schematic plan view of the component surface 10 of the component 12, onto which a plurality of laser beams 14 are aligned one behind the other in the feed direction V, wherein a diameter d of respective images 22 of the laser beams 14 decreases towards the front in the feed direction V, in this case decreases continuously. The further forward in the row of laser beams 14 a respective laser beam 14 is arranged, the smaller the diameter d of its image 22 on the component surface 10. Fig. 13b shows a diagram in which the respective diameters d of the images 22 for the respective laser beams 14 from Fig. 13a are plotted, wherein the respective percentage deviation of the respective diameter d from a reference diameter is plotted on the ordinate.

[0129] A specific example of these embodiments is described below: In this example, laser welding of metallic components based on iron, aluminum, or copper, or mixed joints, takes place, wherein the sheet thickness of a joining partner is in the range of 7 pm - 20 mm, in particular in the range of 75 pm - 500 pm for foils or in the range of 500 pm - 5 mm for sheets, e.g., for battery production. Laser beam sources are single-mode lasers with 100-3000 W per beam source or multi-mode lasers with 1000-100,000 W per beam source; in particular, the total power at the workpiece is 50-30,000 W per MultiSpot line—which refers to a series of laser beams 14 arranged one behind the other in the feed direction V. The laser power per laser beam 14 is in the range 10-10000 W. It is intended that at least one optical element is used to split at least one input laser beam into several individual beams, e.g.The individual beams are generated by diffractive beam splitters, whose diffraction orders can be distributed within the volume of a focusing device. Each diffraction order is spatially controlled by a holographic wedge (transverse) and by a holographic lens (longitudinal -> defocus). Due to the defocus, the component "senses" multiple images 22 with different diameters d. In addition, each diffraction order can have a different weighting due to interference effects. Possible embodiments are: phase modulation through optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence through nanogratings in glasses or polymers, additively manufactured (2PP) optics, etc.), alternatively phase modulation through one or more microlens arrays connected in series.The phase modulation can be imposed on an illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, 8-level DOEs).

[0130] Multiple laser beams from one laser beam source and one optical system can be used. Alternatively, multiple laser beams from at least two laser beam sources and one optical system can be used. Alternatively, multiple laser beams from one laser beam source and at least two optical systems can be used. Alternatively, multiple laser beams from at least two laser beam sources and at least two optical systems can be superimposed.

[0131] The beam parameter product is in the range of 0.38–30 mm*mrad, in particular in the range of 0.4–0.6 mm*mrad (single-mode) or in the range of 2–4 mm*mrad (multi-mode). The diameter d1 of the first image 22 of the series of laser beams 14 on the component surface 10 is in the range of 10 pm–3000 pm, in particular 30 pm–50 pm (single-mode) and 50 pm–1500 pm (multi-mode). A linear arrangement of the images 22 is provided, preferably without lateral offset, alternatively with a lateral offset of at most d ma x (d ma x is the maximum diameter of the largest image 22 on the component surface 10). The distance between the respective edges of the images 22 is preferably at least d max. Each intensity profile of an individual laser beam can consist of a core and a ring component, with the intensity being higher in the core than in the ring. In particular, an infrared laser with a wavelength in the range 800-1200 nm, in particular 1030 nm or 1070 nm or 1080 nm is used. Alternatively, a VIS laser is used, in particular a VIS laser with a wavelength of 400-450 nm (blue) and 515 nm (green). The implemented feed rate is in the range 50 mm / s to 10,000 mm / s, in particular 300-4,000 mm / s. PFO33-2 with an imaging ratio of 1:1 to 5:1, in particular 1.5:1 to 2:1, is used as scanner optics. Alternatively, a BEO flying optics with the same imaging ratios is used.

[0132] By using at least three laser beams 14, in particular 3 to 50 laser beams 14, arranged in a row in the feed direction V, the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is extended, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0133] In the embodiment shown in Fig. 11a, it is provided that the diameters D of at least two of the images 22 decrease counter to the feed direction V. Since the melt pool heats up counter to the feed direction V, decreasing diameters d of the images 22 counteract an increase in the vapor capillary sizes, whereby the melt pool is stabilized.

[0134] In the embodiment shown in Fig. 12a, it is provided that at least one local maximum of the diameters d of the images 22 exists, which is characterized by the fact that an image with a smaller diameter d exists before and after the image along the feed direction V. A resulting reduced temperature gradient in both directions along the feed direction V leads to less susceptibility to cracking. Furthermore, a melt pool with advantageous flow properties is created, which can, for example, reduce humping.

[0135] In the embodiment shown in Fig. 13a, it is provided that the diameters D of at least two of the images 22 increase counter to the feed direction V. The leading, smaller images 22 have a preheating and cleaning effect, whereby welding defects such as pores, spatter and ejections can be reduced.

[0136] The laser beams are arranged one behind the other in the feed direction, in particular without lateral offset from each other, alternatively with a lateral offset of at most the maximum diameter d max of the images 22 on the component surface 10. As a result, the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is lengthened, which can prevent welding defects. This makes it possible to achieve particularly high welding speeds. It is intended that a distance between the respective edges of the images 22 of the laser beams 14 on the component surface 10 corresponds to at least one largest diameter d of the images 22 on the component surface 10. This makes it possible to achieve a particularly long melt pool and, as a result, a particularly high welding speed due to particularly little humping. Furthermore, it is intended that differences in laser power between the laser beams are at least 5 percent, which means that the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is lengthened, which can prevent welding defects.This allows particularly high welding speeds to be achieved.

[0137] It is intended that at least one of the laser beams 14 does not generate a vapor capillary (heat conduction welding) and at least one of the laser beams 14 generates a vapor capillary (deep penetration welding). Furthermore, it is intended that a continuous wave laser beam source with optionally modulated laser power or a pulsed laser beam source is used, with the modulation amplitude being at least 10 percent of the maximum power. This ensures that the melt solidifies particularly slowly in the downstream part of the process zone, as the melt pool is extended, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0138] When used for bipolar plates of a fuel cell or electrolyzer, or for cooler plates for a battery, tight seams, low heat input, and high productivity can be achieved. When used for welding two battery components, especially cell contacts, particularly high strength and particularly low heat input can be achieved. Furthermore, a particularly high welding speed can be achieved. When used for aluminum foil stacks (for batteries), slim seams with short interaction times can be created, which tend to reduce cracking. When used for pipes and profiles, particularly high welding speeds can be achieved.

[0139] In particular, it is intended that the distance between the edges of the respective images 22 corresponds at least to the diameter d of the images 22 on the component surface 10. This allows the vapor capillary and the energy input to be stabilized. Furthermore, a precise penetration depth can be achieved over the entire weld seam, thus achieving a particularly high gas tightness of the weld seam.

[0140] In particular, it is provided that each laser beam 14 consists of a core region and a ring region, in particular by superimposing two beams with preferably congruent optical axes and different beam diameters. In particular, the power component in the core beam is at least 20% of the total power of the respective laser beam 14.

[0141] To stabilize the vapor capillaries, a fiber optic cable (FOC) with 2-in-1 technology, i.e., a ring fiber and a core fiber, can be used. A 2-in-1 main beam is split into several individual beams. The power in the core portion and / or the ring portion can be modulated or pulsed to stabilize the melt pool.

[0142] The following describes a cost-effective, robust, easy-to-adjust, space-saving, and high-performance solution: Generation of the individual beams by diffractive 3D beam splitters, whose diffraction orders can be distributed within the volume of a focusing device. Each diffraction order is spatially controlled by a holographic wedge (transverse) and a holographic lens (longitudinal -> defocus). Due to the defocus, the component 10 "senses" several images 22 that have different diameters d. In addition, each diffraction order can have a different weighting due to interference effects. Possible embodiments include: phase modulation through optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence through nanogratings in glasses or polymers, additively manufactured (2PP) optics, etc.), or phase modulation by one or more series-connected microlens arrays. The phase modulation can be applied to an illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, or 8-level DOEs).

[0143] The beam bundle can be generated by a multi-fiber array, allowing each individual laser beam to be controlled by a laser module. For process stabilization, the laser beams, each forming a vapor capillary, can be modulated or pulsed in different operating modes.

[0144] The drawing shows, in Fig. 14, a schematic representation of several basic shapes 30 and several combination shapes 32 of possible intensity profiles of the laser beams 14 in cross-section. It can be seen that the laser beams 14 can have, for example, a ring shape R, a Gaussian shape G, or a top-hat shape T as their basic shape as an intensity profile. Alternatively, the laser beams 14 can have mixed forms of these basic shapes as their respective intensity profiles, as indicated by the reference numeral 32. In the diagram in Fig. 14, the intensity I is plotted on the ordinate.

[0145] 15 to 17, the intensity I is plotted on the ordinate, with the laser beams 14 arranged one behind the other in the feed direction V being shown next to one another on the abscissa. The “x” axis runs in the feed direction V. In Fig. 15 to Fig. 17, a diagram is shown for respective intensity profiles of the plurality of laser beams 14 arranged one behind the other in the feed direction V and directed onto the component surface 10 of the component 12, wherein the intensity profiles of the respective laser beams 14 each comprise a Gaussian core region and an annular region 26 surrounding the core region 24 in a ring shape.

[0146] In the embodiment shown in Fig. 15, it is provided that the proportion of the ring region 26 in the total intensity of the respective laser beam 14 decreases towards the front in the feed direction V. The further forward in the feed direction V the respective laser beam 14 is arranged in the row, the smaller the proportion of the ring region 26 in the total intensity and the higher the proportion of the core region 24 in the total intensity.

[0147] In the embodiment shown in Fig. 16, it is provided that the proportion of the ring region 26 in the total intensity of the laser beams 14 represents a local maximum for a central one of the laser beams 14. The fact that at least one local maximum exists for the proportion of the ring region 26 in the total intensity of the laser beams 14 is characterized in that laser beams 14 arranged before and after it along the feed direction V each have a smaller proportion of the ring region 26 in the total intensity.It is thus provided that the laser beam 14, which has the higher proportion of the total intensity assigned to the ring region 26 compared to both the laser beam 14 immediately preceding in the feed direction V and the laser beam 14 immediately following in the feed direction V, has the largest proportion of the total intensity in the ring region 26 compared to all other laser beams 14 of the laser beams 14 arranged one behind the other in the feed direction V. Starting from this laser beam 14 having the largest proportion of the total intensity in the ring region 26, the proportions of the ring regions 26 in the total intensity of the other laser beams decrease towards the respective end of the row of laser beams 14 running in the feed direction V, in this case continuously.In the embodiment shown in Figure 17, it is provided that the proportion of the ring region 26 in the total intensity of the respective laser beam 14 increases towards the front in the feed direction V. The further forward in the feed direction V the respective laser beam 14 is arranged in the row, the greater the proportion of the ring region 26 in the total intensity and the smaller the proportion of the core region 24 in the total intensity.

[0148] A specific example of these embodiments is described below: In this example, laser welding of metallic components based on iron, aluminum, or copper, or mixed joints, takes place, wherein the sheet thickness of a joining partner is in the range of 7 pm - 20 mm, in particular in the range of 75 pm - 500 pm for foils or in the range of 500 pm - 5 mm for sheets, e.g., for battery production. Laser beam sources are single-mode lasers with 100-3000 W per beam source or multi-mode lasers with 1000-100,000 W per beam source; in particular, the total power at the workpiece is 50-30,000 W per MultiSpot line—which refers to a series of laser beams 14 arranged one behind the other in the feed direction V. The laser power per laser beam 14 is in the range 10-10000 W. It is intended that at least one optical element is used to split at least one input laser beam into several individual beams, e.g.The individual beams are generated by diffractive beam splitters, which generate diffraction orders. Each diffraction order can be assigned a different optical field (shape) and weighting. The diffractive beam splitter is designed as a hologram that has the far fields of the associated optical fields encoded in amplitude and phase for each diffraction order. Possible embodiments include: phase modulation through optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence through nanogratings in glasses or polymers, additively manufactured (2PP) optics, etc.), or phase modulation through several DOEs (diffractive optical components) connected in series. The phase modulation can be imposed on an illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, 8-level DOEs).

[0149] Multiple laser beams from one laser beam source and one optical system can be used. Alternatively, multiple laser beams from at least two laser beam sources and one optical system can be used. Alternatively, multiple laser beams from one laser beam source and at least two optical systems can be used. Alternatively, multiple laser beams from at least two laser beam sources and at least two optical systems can be superimposed.

[0150] The beam parameter product is in the range of 0.38–30 mm*mrad, in particular in the range of 0.4–0.6 mm*mrad (single-mode) or in the range of 2–4 mm*mrad (multi-mode). The diameter d1 of the first image 22 of the series of laser beams 14 on the component surface 10 is in the range of 10 pm–3000 pm, in particular 30 pm–50 pm (single-mode) and 50 pm–1500 pm (multi-mode). A linear arrangement of the images 22 is provided, preferably without lateral offset, alternatively with a lateral offset of at most d ma x (d ma x is the maximum diameter of the largest image 22 on the component surface 10). The distance a between the images 22 is preferably at least d max. Each intensity profile of an individual laser beam can consist of a core and a ring component, with the intensity being higher in the core than in the ring. In particular, an infrared laser with a wavelength in the range 800-1200 nm, in particular 1030 nm or 1070 nm or 1080 nm is used. Alternatively, a VIS laser is used, in particular a VIS laser with a wavelength of 400-450 nm (blue) and 515 nm (green). The implemented feed rate is in the range 50 mm / s to 10,000 mm / s, in particular 300-4,000 mm / s. PFO33-2 with an imaging ratio of 1:1 to 5:1, in particular 1.5:1 to 2:1, is used as scanner optics. Alternatively, a BEO flying optics with the same imaging ratios is used.

[0151] By using at least three laser beams 14, in particular 3 to 50 laser beams 14, arranged in a row in the feed direction V, the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is extended, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0152] In the embodiments shown in Figs. 15 to 17, it is provided that the intensity profiles of at least two laser beams 14 differ from one another with regard to their intensity profile, in particular in their basic shape (Gaussian shape G, ring shape R, top-hat shape T or combination shape 32). This can achieve a broadening of the melt pool and a stabilization of the vapor capillary. In particular, it is provided that each laser beam 14 comprises a core region 24 and a ring region 26 by superimposing two partial laser beams with preferably congruent optical axes and different beam diameters. In particular, it is provided that the power component in the core region 24 is at least 20 percent of the total power of the respective laser beam 14. This can achieve a stabilization of the vapor capillary.

[0153] To stabilize the vapor capillary, it is particularly intended that a fiber optic cable (LLK) with 2-in-1 technology, i.e. ring and core fiber, is used, whereby a 2-in-1 main beam is divided into several individual beams.

[0154] A widening of the melt pool and a stabilization of the vapor capillary can be achieved if the power distribution between the core region 24 and the ring region 26 differs by at least 5 percent in at least 2 laser beams and the share of the ring region 26 in the total intensity of the respective laser beam 14 increases against the feed direction V or decreases against the feed direction V or the share of the ring region 26 in the total intensity of the respective laser beam 14 represents a local maximum for one of the laser beams 14 which is not arranged at the very front or at the very back in the row.

[0155] Stabilization of the melt pool can be achieved by modulating or pulsing the power in the core part and / or the ring part.

[0156] The laser beams are arranged one behind the other in the feed direction V, in particular without lateral offset from each other, alternatively with a lateral offset of at most the maximum diameter d max of the images 22 on the component surface 10. As a result, the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is lengthened, which helps prevent welding defects. This allows particularly high welding speeds to be achieved. It is intended that a distance a between the images 22 of the laser beams 14 on the component surface 10 corresponds to at least one largest diameter d of the images 22 on the component surface 10. This allows a particularly long melt pool and, consequently, a particularly high welding speed to be achieved due to particularly little humping.

[0157] It is intended that at least one of the laser beams 14 does not generate a vapor capillary (heat conduction welding) and at least one of the laser beams 14 generates a vapor capillary (deep penetration welding). Furthermore, it is intended that a continuous wave laser beam source with optionally modulated laser power or a pulsed laser beam source is used, with the modulation amplitude being at least 10 percent of the maximum power. This ensures that the melt solidifies particularly slowly in the downstream part of the process zone, as the melt pool is extended, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0158] When used for bipolar plates in a fuel cell or electrolyzer, tight seams, low heat input, and high productivity can be achieved. When used for welding two battery components or a cooler plate, high strength and low heat input can be achieved. When used for aluminum foil stacks (for batteries), slim seams with short interaction times can be created, which tend to reduce cracking. When used for tubes and profiles, high feed rates can be achieved.

[0159] If the distance a between the images 22 is at least as large as their diameter d on the component surface 10, the vapor capillary and, consequently, the energy input can be stabilized. Furthermore, a precise penetration depth can be achieved along the entire weld seam, thus achieving a particularly high gas-tightness of the weld seam.

[0160] The beam diameters of the laser beams 14 are preferably identical. Alternatively, the largest individual beam diameter can be a maximum of ten times larger than the smallest beam diameter. This allows for the creation of slim seams that allow for particularly low heat input.

[0161] The following describes a cost-effective, robust, easy-to-adjust, space-saving, and high-performance solution: Generation of the individual beams using diffractive 3D beam splitters that generate diffraction orders. Each diffraction order can be assigned a different optical field (shape) and weighting. The diffractive beam splitter is designed as a hologram that encodes the far fields of the associated optical fields for each diffraction order in amplitude and phase. Possible embodiments include phase modulation through optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence through nanogratings in glasses or polymers, additively manufactured (2PP) optics, etc.), or phase modulation through multiple DOEs connected in series.The phase modulation can be imposed on an illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, 8-level DOEs).

[0162] The beam can be generated by a multi-fiber array, with modes or mode groups selectively excited in each fiber, allowing each individual laser beam 14 to be controlled by a laser module. For process stabilization, the laser beams, each forming a vapor capillary, can be modulated or pulsed in different operating modes.

[0163] 18 and 19 show respective embodiments in which a plurality of laser beams 14 are directed onto the component surface 10 of the component 12 in respective rows running one behind the other in the feed direction V. In other words, a plurality of parallel rows of laser beams 14 are directed onto the component surface 10, each row comprising a plurality of laser beams 14 arranged one behind the other in the feed direction V. In the embodiments shown in Figs. 18 and 19, all rows comprise the same number of laser beams 14 and the rows have at least substantially no offset from one another in the feed direction V. In the embodiments shown in Figs. 18 and 19, it is provided that three rows of laser beams 14 are directed onto the component surface 10. In the embodiment shown in Fig.In the embodiment illustrated in Figure 18, it is provided that the lateral spacing between the rows is so large that each of the rows forms a separate molten pool, whereby a separate weld seam is formed for each row of laser beams 14. The shortest lateral spacing (in a direction perpendicular to the feed direction V and parallel to the component surface 10) between each two adjacent rows is at least three times, in particular at least five times, the diameter d of the projections 22 of the laser beams 14 on the component surface 10.

[0164] In the embodiment shown in Fig. 19, the lateral spacing between the rows is so small that all rows form a common molten pool. As a result, a weld seam with a particularly large width can be produced. The shortest lateral spacing (in a direction perpendicular to the feed direction V and parallel to the component surface 10) between any two adjacent rows is less than three times the diameter d of the projections 22 of the laser beams 14 on the component surface 10.

[0165] Fig. 20 shows a schematic sectional view of the component 12, onto which the plurality of laser beams 14 are aligned one behind the other in the feed direction V. It can be seen that the focal positions 34 of the laser beams 14 within a row increase towards the front in the feed direction V. The focal positions 34 are arranged at different heights in a direction perpendicular to the component surface 10. The further a laser beam 14 is arranged towards the front in the row in the feed direction V, the higher its focal position 34 is. In the embodiment shown in Fig. 20, it is provided that the focal positions 34 of the laser beams 14 arranged one behind the other in the feed direction V increase continuously upwards.

[0166] Fig. 21 shows a schematic sectional view of the component 12, onto which a plurality of laser beams 14 are aligned one behind the other in at least two rows in the feed direction V. The focal positions 34 of the laser beams 14 within a respective row increase the further the respective laser beam 14 is arranged to the front in the respective row in the feed direction V. Furthermore, in the embodiment shown in Fig. 21, it is provided that the focal positions 34 of the at least two rows of laser beams 14 differ from one another in their height in a direction running perpendicular to the component surface 10, at least with regard to one laser beam 14. Fig. 21 therefore shows a combination of two rows of laser beams 14.The rows each have focus positions 34 which rise forward in the feed direction V, the focus positions 34 of the laser beams 14 of one of the rows being higher than the focus positions 34 of the laser beams 14 of the other row in a direct comparison of the respective laser beams 14 arranged next to one another in a direction running perpendicular to the feed direction V and parallel to the component surface 10. If a straight line were to be drawn through the focus positions 34 of the respective laser beams 14 of a common row of laser beams 14 arranged one behind the other in the feed direction V, then one straight line of one of the rows would be arranged higher than the other in the direction running perpendicular to the component surface 10.

[0167] Fig. 22 shows a schematic plan view of the component surface 10 of the component 12, onto which a plurality of laser beams 14 are aligned one behind the other in respective rows running in the feed direction V. Here, it is provided that at least two of the rows have a relative offset to one another in the feed direction V. In other words, the laser beams 14 of one of the rows are arranged offset forward in the feed direction relative to the laser beams 14 of the other row. In the embodiment shown in Fig. 22, three rows of laser beams 14 running parallel to one another are aligned onto the component surface 10, wherein the laser beams 14 of one of the rows are arranged offset forward in the feed direction V relative to the laser beams 14 of the other two rows.In the embodiment shown in Figure 22, it is provided that within the respective rows, the laser beams 14 are spaced apart by the same distance from one another in the feed direction V, wherein the distances between the laser beams 14 within the rows are the same for all rows. In this case, it is further provided that the last laser beam 14 of one of the rows in the feed direction V is offset forward in the feed direction by at least 10 percent of the diameter d of the respective images 22 of the laser beams 14 on the component surface 10 compared to the last laser beams 14 of the other rows in the feed direction V.

[0168] Fig. 23 shows a schematic plan view of the component surface 10 of the component 12, wherein a plurality of laser beams 14 are aligned one behind the other on the component surface 10 in respective rows running in the feed direction V, wherein the respective rows comprise a different number of laser beams 14. In the present case, it is provided that a main row comprises eight laser beams 14 and two secondary rows, each with two laser beams 14, are provided. The secondary rows run parallel to the main row and are arranged on opposite sides of the main row in a direction running parallel to the component surface 10 and perpendicular to the feed direction V.The secondary rows enable lateral heating of the component surface 10 next to the main row, whereby a particularly low temperature gradient can be achieved, whereby the formation of humping, cracks and inhomogeneities in the melt pool can be particularly well limited and in particular avoided.

[0169] A specific example of these embodiments is described below: In this example, laser welding of metallic components based on iron, aluminum, or copper, or mixed joints, takes place, wherein the sheet thickness of a joining partner is in the range of 7 pm - 20 mm, in particular in the range of 75 pm - 500 pm for foils or in the range of 500 pm - 5 mm for sheets, e.g., for battery production. Laser beam sources are single-mode lasers with 100-3000 W per beam source or multi-mode lasers with 1000-100,000 W per beam source; in particular, the total power at the workpiece is 50-30,000 W per MultiSpot line—which refers to a series of laser beams 14 arranged one behind the other in the feed direction V. The laser power per laser beam 14 is in the range 10-10000 W. It is intended that at least one optical element is used to split at least one input laser beam into several individual beams, e.g.The individual beams are generated by diffractive beam splitters, whose power components (weightings) are controlled by the grating geometry, in particular by the phase modulation of a periodically extended unit cell. If the beam splitting takes place in two dimensions (two spatial directions), the grating distribution is also two-dimensional, as is the corresponding unit cell. Possible embodiments are: phase modulation by optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence by nanogratings in glasses or polymers, additively manufactured (2PP) optics, etc.), or alternatively, phase modulation by several microlens arrays connected in series. The phase modulation can be imposed on an illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, 8-level DOEs).

[0170] Multiple laser beams from one laser beam source and one optical system can be used. Alternatively, multiple laser beams from at least two laser beam sources and one optical system can be used. Alternatively, multiple laser beams from one laser beam source and at least two optical systems can be used. Alternatively, multiple laser beams from at least two laser beam sources and at least two optical systems can be superimposed.

[0171] The beam parameter product is in the range of 0.38–30 mm*mrad, in particular in the range of 0.4–0.6 mm*mrad (single-mode) or in the range of 2–4 mm*mrad (multi-mode). The diameter d1 of the first image 22 of the series of laser beams 14 on the component surface 10 is in the range of 10 pm–3000 pm, in particular 30 pm–50 pm (single-mode) and 50 pm–1500 pm (multi-mode). A linear arrangement of the images 22 is provided, preferably without lateral offset, alternatively with a lateral offset of at most d ma x (d ma x is the maximum diameter of the largest image 22 on the component surface 10). The distance a between the images 22 is preferably at least d max. Each intensity profile of an individual laser beam can consist of a core and a ring component, with the intensity being higher in the core than in the ring. In particular, an infrared laser with a wavelength in the range 800-1200 nm, in particular 1030 nm or 1070 nm or 1080 nm is used. Alternatively, a VIS laser is used, in particular a VIS laser with a wavelength of 400-450 nm (blue) and 515 nm (green). The implemented feed rate is in the range 50 mm / s to 10,000 mm / s, in particular 300-4,000 mm / s. PFO33-2 with an imaging ratio of 1:1 to 5:1, in particular 1.5:1 to 2:1, is used as the scanner optics. Alternatively, a BEO flying optics with the same imaging ratios is used.

[0172] By using at least three laser beams 14, in particular 3 to 50 laser beams 14, arranged in a row in the feed direction V, the melt solidifies particularly slowly in the downstream part of the process zone because the melt pool is extended, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0173] If at least two laser beams 14 are provided with a different focal position 34 from one another, in particular if the difference between the focal positions 34 is greater than 5% of the Rayleigh length of one of the laser beams 14, then an increased focal position tolerance can be achieved. In particular, this focal position offset is provided between two laser beams 14 that are arranged next to one another in the feed direction V or in a direction perpendicular to the feed direction V and parallel to the component surface 10.

[0174] In particular, the difference between the positions of the focus positions 34 of the two laser beams 14 is at least 10 percent of the diameter d of the images 22 on the component surface 10. This enables a particularly high image density with a sufficiently large distance a between the images 22.

[0175] The provision of parallel secondary rows with fewer laser beams 14 than in the main row enables lateral heating of the component surface 10 next to the main row, which leads to reduced temperature gradients and thus to less humping, cracks or inhomogeneities in the melt pool.

[0176] The provision of parallel rows of laser beams 14 with separate melt pools enables the simultaneous production of parallel weld seams, thereby achieving particularly high productivity. The provision of parallel rows of laser beams 14 with overlapping melt pools enables the production of particularly wide weld seams.

[0177] It is intended that a distance a between the images 22 of the laser beams 14 on the component surface 10 corresponds to at least one largest diameter d of the images 22 on the component surface 10. This allows for a particularly long molten pool and, consequently, a particularly high welding speed due to particularly low humping. Furthermore, it is intended that differences in laser power between the laser beams be at least 5 percent, whereby the melt solidifies particularly slowly in the downstream part of the process zone because the molten pool is extended, thus avoiding welding defects. This allows for particularly high welding speeds to be achieved.

[0178] It is intended that at least one of the laser beams 14 does not generate a vapor capillary (heat conduction welding) and at least one of the laser beams 14 generates a vapor capillary (deep penetration welding). Furthermore, it is intended that a continuous wave laser beam source with optionally modulated laser power or a pulsed laser beam source is used, with the modulation amplitude being at least 10 percent of the maximum power. This ensures that the melt solidifies particularly slowly in the downstream part of the process zone, as the melt pool is lengthened, thus avoiding welding defects. As a result, a particularly high welding speed can be achieved.

[0179] When used for bipolar plates in a fuel cell or electrolyzer, tight seams, low heat input, and high productivity can be achieved. When used for welding two battery components or a cooler plate, high strength and low heat input can be achieved. When used for aluminum foil stacks (for batteries), slim seams with short interaction times can be created, which tend to reduce cracking. When used for tubes and profiles, high feed rates can be achieved.

[0180] If the distance a between the images 22 is at least as large as their diameter d on the component surface 10, the vapor capillary and, consequently, the energy input can be stabilized. Furthermore, a precise penetration depth can be achieved along the entire weld seam, thus achieving a particularly high gas-tightness of the weld seam.

[0181] The beam diameters of the laser beams 14 are preferably identical. Alternatively, the largest individual beam diameter can be a maximum of ten times larger than the smallest beam diameter. This allows for the creation of slim seams that allow for particularly low heat input.

[0182] In particular, it is provided that each laser beam 14 consists of a core region and a ring region, in particular by superimposing two beams with preferably congruent optical axes and different beam diameters. In particular, the power component in the core beam is at least 20% of the total power of the respective laser beam 14.

[0183] To stabilize the vapor capillaries, a fiber optic cable (FOC) with 2-in-1 technology, i.e., a ring fiber and a core fiber, can be used. A 2-in-1 main beam is split into several individual beams. The power in the core portion and / or the ring portion can be modulated or pulsed to stabilize the melt pool.

[0184] The following describes a cost-effective, robust, easy-to-adjust, space-saving, and high-performance solution: Generation of the individual beams using diffractive beam splitters, which generate diffraction orders whose power components (weightings) are controlled by the grating geometry, in particular by the phase modulation of a periodically extended unit cell. If the beam splitting occurs in two dimensions (two spatial directions), the grating distribution is also two-dimensional, as is the corresponding unit cell.

[0185] Possible embodiments are: phase modulation by optical path length differences (etched height profile in fused silica, height profile in copper, birefringence in liquid crystals, birefringence by nanogratings in glasses (geometric phase holograms) or polymers, additively manufactured (2PP) optics, etc.), alternatively phase modulation by one or more series-connected microlens arrays. The phase modulation can be imposed on an illumination beam as a continuous distribution or approximated by discrete phase values ​​(2-, 4-, 8-level DOEs). The beam bundle can be generated by a multi-fiber array, whereby each laser beam 14 can be controlled by a laser module. For a

[0186] For process stabilization, the laser beams, each forming a vapor capillary, can be modulated or pulsed in different operating modes.

[0187] Overall, the invention shows how multi-spot “inline” laser welding can be implemented.

[0188] LIST OF REFERENCE SYMBOLS

[0189] 10 Component surface

[0190] 12 components

[0191] 14 Laser beam

[0192] 16 welding track

[0193] 18 Weld seam

[0194] 20 Welding direction

[0195] 22 Figure

[0196] 24 Core area

[0197] 26 ring area

[0198] 28 width

[0199] 30 basic shapes

[0200] 32 combination forms

[0201] 34 Focus position a n Distance

[0202] C n Cluster d n diameter

[0203] V feed direction

[0204] R ring shape

[0205] G Gaussian shape

[0206] T Top-Hat-Shape

[0207] I Intensity

Claims

PATENT CLAIMS 1. A method for welding at least two components (12) along a welding path (16) running on a component surface (10) of at least one of the components (12), in which at least three laser beams (14), in particular 5 to 30 laser beams (14), are aligned simultaneously one after the other onto the welding path (16) and are moved over the component surface (10) at the same feed rate in a welding direction (20) running along the welding path (16), wherein during the movement of the laser beams (14) in the welding direction (20) laser power is introduced into at least one of the components (12) by means of each of the laser beams (14).

2. Method according to claim 1, characterized in that the laser beams (14) are arranged one behind the other in a straight line.

3. Method according to claim 1 or 2, characterized in that respective parameters are set for at least one of the laser beams (14) in such a way that a vapor capillary is generated.

4. Method according to claim 3, characterized in that for all laser beams (14) respective parameters are set such that one vapor capillary is generated per laser beam (14).

5. Method according to one of the preceding claims, characterized in that a distance between the centers of images (22) of two laser beams (14) arranged one behind the other along the welding path (16) is greater than at least 20% of a width (28) of a weld seam (18) produced by the welding, said width running perpendicular to the welding direction (20) and on the component surface (10).

6. Method according to one of the preceding claims, characterized in that a distance between the centers of images (22) of two laser beams (14) arranged one behind the other along the welding path (16) is greater than a diameter of the respective images (22).

7. Method according to one of claims 1 to 4, characterized in that a first distance between the centers of two images of respective laser beams arranged directly one behind the other in the feed direction and a second distance between the centers of two images of respective laser beams arranged directly one behind the other along the welding path differ from each other by at least 5 percent, in particular by at least 10 percent, in particular by at most 500 percent.

8. Method according to one of the preceding claims, characterized in that Differences in laser power between the laser beams (14) may not exceed 80%, in particular not exceed 20%.

9. Method according to one of claims 1 to 7, characterized in that at least two laser beams differ from each other with regard to laser power and / or laser intensity by at least 5 percent, in particular by at least 20 percent.

10. Method according to one of the preceding claims, characterized in that at least two images of two of the laser beams on the component surface differ from one another in their diameter by at least 5 percent, in particular by at least 20 percent, in particular by at most 1000 percent.

11. Method according to one of the preceding claims, characterized in that at least one of the laser beams (14) comprises a core beam and a core beam annularly enclosing cladding beam, wherein it is particularly provided that the core beam has at least 80% of a total laser power of the laser beam (14).

12. Method according to claim 8, characterized in that the laser power of the core beam and / or the laser power of the cladding beam is varied periodically, wherein during welding by means of this laser beam (14) laser power is continuously introduced into at least one of the components (12).

13. Method according to one of the preceding claims, characterized in that at least two of the laser beams arranged one behind the other in the feed direction have a cross-sectional intensity profile which differs from one another.

14. Method according to one of the preceding claims, characterized in that at least two laser beams are arranged next to one another in a direction running obliquely or perpendicular to the feed direction.

15. Method according to one of the preceding claims, characterized in that a focus position in a direction perpendicular to the component surface of at least two of the laser beams differs from each other, in particular by more than 5 percent of the Rayleigh length of one of the laser beams.

16. Laser welding device for welding at least two components (12) along a welding path (16) running on a component surface (10) of at least one of the components (12), which is designed to align at least three laser beams (14), in particular 5 to 30 laser beams (14), simultaneously one after the other onto the welding path (16) and to move them at the same feed speed in a welding direction (20) running along the welding path (16) over the component surface (10), wherein during Moving the laser beams (14) in the welding direction (20) by means of each of the laser beams (14) laser power is introduced into at least one of the components (12).

Images